as he first posted "used F10 to save changes and exit".
Now reports CMOS battery good.
Some mobo's have a jumper to "clear CMOS" by moving it from pins 1-2 to 2-3, to get rid of a password, AND you don't get a boot message that you left it on 2-3, thereby clearing CMOS every boot.
IF the jumper is not the problem (or other method of clearing CMOS), then the CMOS battery is not making connection on the mobo, and that's a hairy deal to investigate. I've only seen this once, where someone pried out the battery and broke off the + contact strip on the side of the battery socket.
If the BIOS chip was bad, you'd see many more errors at boot.
Since your PC WAS keeping time OK, Y2K date change was not an issue.
Meteor dust has been known to give "awareness" to a PC and it rebels it's servitude to humans.