Seems quite a lot of people have trouble with system restore points.
I disable system restore functionality on my machines, as I use regular image backups for my system, and my system and data files are kept in separate partitions on my machines. One reason for disabling the system restore functionality is to save space, and reduce the size of backup images!
If you keep on setting system restore points, and a lot of software does this automatically, ( if it can!
) then you just keep on adding rubbish to your partitions.
Here are clear instructions on how to disable system restore for XP;
http://support.microsoft.com/kb/310405
ONLY DO THIS IF YOU MAKE REGULAR SYSTEM BACKUPS!
Regards.....
Mike Connor