Froze - Had to reset CMOS - Why?

[krips]

Here's the info: I went to switch users, but it wouldn't let me (error message). Then I tried to log off. It froze. Then I hit the restart button. It would 1/2 start up...the led on the CDROM drive would keep flashing off and on. A reset of the CMOS solved the problem...any idea what could've caused it?