It sounds like you must have had a problem which caused the computer to reset to an older registry point. Windows xp automatically sets registry points when you load or unload software/hardware etc. If you are using XP you can go into programs/system/system restore and try to change to a more recent registry point . maybe one that is only a couple of weeks old. If XP cannot do this it will revert back to the one you were most recently using.
sharon
December 2007