If you have Vista installed on the same PC, Vista will remove the restore points from XP.

There are registry settings to control how often restore points are made and how long they are kept.  Some malware may have trashed your settings.   Mine works just fine.

How do you know if its working, you asked?
Open the program and see if there are any restore points recorded there and at what frequency.
I've never had time to investigate why some PC's get a new restore point every day and others only on specific Events.  On those that are not getting daily restore points I just install my little script and then I don't worry any more about it.

What really blows my mind is the person that never turns off their PC.
I'll say it for the 1,399th time.....XP was never designed to run like a Server (24x7).  That's why MS created a special OS for that, specifically called "Server".
Restore points don't get made and the registry never gets updated, because updates are held in ram and never get saved to the master registry on the HD.  Then if the computer crashes due to a power failure or other failure, all those registry updates are lost forever.

Save the electricity and save your PC.....TURN IT OFF WHEN YOU'RE DONE USING IT.

Happy Thanksgiving Everyone!