On an XP computer, there is no benefit in having System Restore on any partition that does not have the OS (Operating System).
System Restore monitors a core set of system and application files, archiving the states of these files before system changes are made. System Restore also saves a full snapshot of the registry and some dynamic system files. When System Restore detects that the user is not actively using the computer, it compresses the registry and any file copies made.
System Restore requires a minimum of 200 MB of free disk space on the system drive at installation. When the amount of free disk space falls below 50 MB on any drive, System Restore switches to standby mode and stops creating restore points. All restore points are deleted at that time. System Restore reactivates and resumes creating restore points as soon as 200 MB of disk space is free on the system drive.
The files that are monitored or excluded from monitoring are specified in the file %windir%\system32\restore\Filelist.xml. For more information, see Monitored File Extensions.http://msdn.microsof..._extensions.asp
If you turn off system restore and turn it back on and it works again, the reason is because one of your restore points is corrupt. If you try to restore your computer to 3 days ago and if one of the restore points made between now and three days ago happens to be corrupted, the restore will fail. It needs to have all restore points between today and the day you're trying to restore to. This is because each time system restore makes a restore point it only backs up the changes that were made since the last restore point was made.