Well I was gonna tell you to get a Linux live CD to get in and back up your stuff, but I see you've got that one covered.

I'd be wary that there might be a hardware issue here; The pattern of the blinking on the capslock/numlock keys is actually a diagnostic code, telling you why the machine won't start up. Older PCs used a similar mechanism, only it was a series of beeps from the PC speaker. Unfortunately there are a number of different problems it could be, so I don't suppose you remember the pattern?

You can have a look <a href="http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01443366&cc=us&dlc=en&lc=en&jumpid=reg_R1002_USEN">here</a> to see if you can match a diagnosis from memory, otherwise make sure you note down the pattern if it happens again. If it doesn't happen again, it was probably just telling you the battery was drained.