There are limits to what Restore can accomplish.
When a Restore Point is established, Restore saves the crucial files that are part of your system's configuration. Among others, these files include those that run Windows and all your programs.
Restore stuffs all those files in one superfile, the cabinet, or cab, file. Every Restore Point, moreover, gets its own cab file.
All the cab files are stored in an area named the Data Store.
But Restore files can be saved only if your hard drive has enough room for the whole Data Store.
If your drive is 2 gigabytes or less, it should have at least 200 megabytes of space free. If the drive is between 2 gigabytes and 4 gigabytes, that required amount is 400 megabytes. If your drive is more than 4 gigabytes, it should have at least 12 percent of its space available.
If Windows cannot find the space it needs to establish the Data Store, it disables System Restore and flushes away existing Restore Points.
That may be why yours are going bye-bye.
Here's another possible villain behind disappearing Restore Points.
When you installed Windows Millennium Edition, it may have decided to set the default size of the Data Store to 200 MB.
Now you come along, and uninstall 250 MB of program and system files. Behind the scenes, Restore tries to save copies of those files in case you want to call them back to duty someday.
But faced with a Data Store that is designed for only 200 MB and the need to store copies of files totaling 250 MB, Windows will do what comes naturally: disable Restore.
So one preemptive measure may be to increase the amount of space allotted to the Data Store, if your hard drive is large enough to accommodate this sort of tinkering.
To adjust the Data Store's size, go to Control Panel, and click on the System icon.
Click the Performance tab.
Click on the File System button, then the Hard Disk tab. Use the slider under "System Restore disk space use" to set the desired size of the Data Store.
Here are some additional wrenches that can bring System Restore to a grinding halt:
A special file, Statemgr.exe, is the power behind System Restore, and needs to load on bootup.
Check the Startup portion of the System Configuration Utility. There has to be a check mark next to the line referring to "*StateMgr" if Restore is to work.
For Restore to work properly, the computer must be idle at least part of the time.
Distributed computing programs that run whenever you are not using the computer do away with idle time.
If you have joined a distributed computing project - such as the Search for Extraterrestrial Intelligence, an effort by astronomers - turn it off for at least a few hours a day to give Restore the time it needs to work.
Computer monitoring programs such as Norton's SystemDoctor may also fool the computer into thinking it has no idle time during which to create Restore Points, according to some techies who have grappled with Restore problems. They say the same is true of antivirus programs.