Two questions:
(1) Have you updated your computer with Windows XP
Service Pack 2?
(2) If you have updated, are you running a HP or Compaq
computer?
Hewlett-Packard says:
<quote>
Update: System Restore
Once you install SP2, you are not able to use System
Restore to go back to a previous restore point unless the
following update (SP26352) has already been installed. If
you have already installed service pack 2 and want to be
able to access restore points that were made before
service pack 2 was installed, uninstall service pack 2
and apply this update:
System Restore Update (in English).
<quote>
If this is the root of your problem, go to the HP website
and download the patch. It is very small and installs
quickly.