Another week, another error

Getting to be an unfortunate habit.

Had bad weather while I was not home, and the power went off enough to
shut down the computer. When I attempted to re-boot, it took several tries - and during one of the tries, at the Windows welcome screen I got the following error;

Isass.exe - System Error
AnI/O operation initiated by the Registry failed unrecoverably. The Registry could not read in, or write out, or flush, one of the files that contain the system's image of the Registry.

I have no clue what that means - but I"m thinking I have some kind of fundamental problem with this computer - every week it seems there is a new and different error to deal with.The machine finally did reboot and come back online normally - except that it had the date at January of 2002. Odd. I changed the date to the current date - is that part of the problem?
Any thoughts, enlightenment, or suggestions as to what to do would be most appreciated.

Thanks again for any help - Martin - are you out there?

Trish