How System Restore Works ?

System Restore automatically tracks changes to your computer and creates restore points before major changes are to occur. To create a restore point, System Restore takes a full snapshot of the registry and some dynamic system files. For a list of what file types are monitored and restored, see Microsoft Windows XP System Restore.
For example, restore points are created before new device drivers, automatic updates, unsigned drivers, and some applications are installed. These healthy system checkpoints are created without prompting or intervention from the user the first time the computer is started after Windows XP is installed and, by default, on a daily basis after that. You can also manually create restore points.
When you use System Restore, you can revert to a saved state without losing personal data including Word documents, e-mail settings and messages, and your Internet favorites list. System Restore won't lose any data you have stored in the My Documents, My Pictures, or My Music folders either.

Disk Space for System Restore
To use System Restore, you'll need 200 MB of free hard disk space, which is used to store the data gathered for the restore points. If you don't have this much free space, System Restore will disable itself until the space becomes available. System Restore will create and save restore points until this space is full, and will then begin writing over itself beginning with the least recent data.
200 MB isn't a lot of room to store restore points. Allocating more space will result in better protection and performance. I'd suggest allocating the maximum amount available. To allocate more than the default 200 MB of disk space to System Restore:
1. Click Start, click Control Panel, click Performance and Maintenance, and then click System.
2. In the System Properties dialog box, on the System Restore tab, use the slider to increase the allocated disk space, and then click OK.
If you're using more than one drive on your system, follow these steps:
1. Click Start, click Control Panel, click Performance and Maintenance, and then click System.
2. Click the drive you want to monitor, and then click Settings.
3. In the Settings dialog box, use the slider to increase the disk space, and then click OK twice.
Notice that the disk space allocated to System Restore cannot exceed 12%. If you need more space, you can run the Disk Cleanup utility to reclaim space. To open Disk Cleanup:
• Click Start, point to All Programs, point to Accessories, point to System Tools, and then click Disk Cleanup.

Before You Try System Restore
System Restore should only be used after trying less comprehensive methods of troubleshooting. System Restore changes many files and registry entries, and in some cases might replace more files than you want restored. So when I first run into a computer problem, I reboot my computer. I'm still amazed at how often a problem is solved by using this simple technique. Or, if your computer won't start in normal mode, reboot your computer, press F8 during the boot process, use the arrow keys to highlight Last Known Good Configuration, and then press ENTER.
Other troubleshooting techniques that often work are listed below.
Run problem applications in Compatibility Mode if system instability occurs after installing a particular application. To run the Program Compatibility Wizard:
• Click Start, point to All Programs, point to Accessories, and then click Program Compatibility Wizard.
Use Add or Remove Programs to uninstall a problem application if the system instability has occurred immediately after a new application has been installed and running the program in Compatibility Mode hasn't helped. Although System Restore will remove the application if you choose to apply it, it is better to remove the offending application from Control Panel.
To open Add or Remove Programs:
1. Click Start, click Control Panel, and then click Add or Remove Programs.
2. Click the program you want to remove, and then click Change/Remove.
If the system's instability has occurred immediately after a new device driver is installed, use the Device Driver Rollback feature instead of System Restore. To roll back to an earlier driver:
1. Right-click My Computer and then click Properties.
2. On the Hardware tab, click Device Manager.
3. In the Device Manager dialog box, double-click the hardware that uses the driver in question.
4. In the device Properties dialog box, on the Driver tab, click Roll Back Driver.
See Charlie Russel's columns, Device Driver Rollback Beats BSOD and Finding Compatible Device Drivers for Windows XP, and Paul McFedries' column, Troubleshoot Device Driver Problems, for more information about device drivers.
Work through the Windows XP troubleshooters in the Help and Support Center.
To open a troubleshooter:
1. Click Start, and then click Help and Support.
2. Under Pick a Help topic, click Fixing a Problem.
3. Under Troubleshooting problems in the right pane, click List of troubleshooters, and then start a troubleshooter by clicking the name in the left column of the table.
If, after trying these options the computer is still unstable, opt for System Restore. You'll want to save this option for last because the changes made to your computer are more comprehensive than if you simply uninstall a program or rollback a device driver.

Use System Restore
After you've decided to use System Restore to revert your system to a previous state, start the System Restore Wizard and follow the prompts. To use the System Restore Wizard, make sure you're logged on as an administrator, and then follow these steps:
1. Click Start, point to All Programs, point to Accessories, point to System Tools, and then click System Restore.
2. On the Welcome screen, click Restore my computer to an earlier time, and then click Next.
3. On the Select a Restore Point page, select the date from the calendar that shows the point you'd like to restore to, as shown in Figure 2, and then click Next.
Figure 2
4. On the Confirm Restore Point Selection page, verify that the correct restore point is chosen, and then close any open programs.
5. Click Next if you are ready to proceed or click Back to change the restore point.
6. The computer will shut down automatically and reboot. On reboot, you'll see the Restoration Complete page, and then click OK.
After reviewing the stability of your system, you can choose another restore point or undo this restoration. Just open System Restore and make the appropriate choice. After you use System Restore, you'll have an additional task; Undo my last restoration, on the System Restore Welcome page. Remember that you'll have to reinstall any programs that were installed after the restore point.
If System Restore doesn't work in Normal Mode, it might work in Safe Mode. To use System Restore in Safe Mode, press the F8 key during reboot and choose Safe Mode. When your computer starts in either Safe Mode or Normal Mode, System Restore can be used to capture a working previous state. System Restore can't be opened unless the system is bootable into one of these modes.

Create Restore Points Manually
Only application installations that use a System Restore restorept.api-compliant installer will trigger the creation of a restore point. So it's a good idea to create a restore point manually before you install an application that you suspect won't have one a restorept.api-compliant installer. For example, before installing a screensaver you've downloaded from the Internet or a beta program from a software vendor, you should manually create a restore point. For more information, see the TechNet article,Windows XP System Restore.
To manually create a restore point:
1. Click Start, point to All Programs, point to Accessories, point to System Tools, and then click System Restore.
2. On the Welcome page, click Create a restore point.
3. On the Create a Restore Point page, enter a descriptive name for your restore point, as shown in Figure 3, and then click Create.
Figure 3
The Restore Point Created page confirms that the new restore point has been created. I think it's a good idea to manually create a restore point before you download and install any application from the Internet.

Use Scheduled Tasks
You can use Scheduled Tasks to create restore points at specified times. You might want to configure Scheduled Tasks to run System Restore at 6:00 P.M. daily, so that you always have a restore point available at the end of each working day.
To create a Scheduled Task, log on as an administrator, and then follow these steps:
1. Click Start, click Control Panel, click Performance and Maintenance, click Scheduled Tasks, and then double-click Add Scheduled Task.
2. Click Next on the first Scheduled Task Wizard page.
3. On the second page, click System Restore in the list of applications, and then click Next.
4. Continue through the wizard, specifying the days and times to run System Restore.
5. When prompted, type in the user name and password for an administrator of the system, and then click Finish.
Scheduled Tasks starts each time you start Windows XP and runs in the background.

Troubleshoot System Restore
Some common problems that could cause System Restore not to work properly and their solutions include the following:
• There is less than 200 MB of free space available on the computer—free up some space on the hard drive by deleting unused files or images.
• After rebooting, the restorations are unsuccessful—choose an earlier restore point and try again.
• Restoration was denied due to non-administrator status—log out and then back in as an administrator.
• The System Restore Service is not running—Open Administrative Tools, click Computer Management, and then click Services and Applications. Click Services, and double-click System Restore Services from the list. Verify the service is started and running. If not, under Service status, click Start and change the startup type to Automatic.
Solutions to more complicated problems can be found in the Microsoft Knowledge Base by clicking Search the Knowledge Base and entering System Restore and a few keywords that describe the problem. For example, System Restore Does Not Restore Printer Drivers to Original State details what to do if System Restore fails to restore printer drivers although the rest of the restore process seems to go smoothly.

Do I Still Have to Use Backup?
System Restore is no substitute for regularly backing up your data. System Restore comes into play when your computer becomes unstable. System Restore can't be used if your hard drive fails or is melted down in a fire, because the information that System Restore uses is stored on the hard drive itself. To create regular backups of your data and computer system state, use the Backup utility in Windows XP.
To open Backup:
• Click Start, point to All Programs, point to Accessories, point to System Tools, and then click Backup.
When you use Backup, save the backup information to a disk or an external drive for safekeeping. If there's a catastrophic failure, such as a hard drive crash, this backup can be used to restore the data after the hardware repair is complete. See Backup and Recover Your Information, Use Backup to Protect Information, and Backup Overview for more coverage on Backup.

I hope you like this post. Please pass your comments.