I just booted my desktop today, and I was greeted with a screen saying my BIOS is in Fail Safe mode. Does that mean my CMOS battery is dead? Or something worse?

I checked my BIOS settings, and everything seems the same as far as I can remember it, but it does this every time on boot up now.

I don't think that PC BIOS systems are in any way standardized. This could be any kind of vendor-specific programming at best, or sabotage at worst (but probably that's too extreme). I suppose it would help to know the make and model of your motherboard. Being more specific would help too. Does it prompt you for input or just halt the system entirely? If you can read the BIOS settings then you must be able to enter that part of the program at least. Preliminary Google searches suggest that some kind of hardware is failing and the BIOS/CMOS is being paranoid.

When I boot it says "System is running in Fail-Safe State. Please recheck - BIOS CMOS SETUP, on a screen that says Phoenix - AwardBIOS v6.00PG. The motherboard is an ABIT KV8 Pro Socket 754 64 bit.

I think it's just a bad CMOS battery, but I have had problems with the graphics driver getting corrupted. The boot screen says memory is OK.

It boots normally after pressing F1 to continue.

Batteries are cheap and easily replaceable. That would be the simplest way to test.

I've had a computer for years that won't keep the battery charged, so I run it without a battery at all. It'll revert to default settings and a date in 2005 if I turn off the power supply rocker switch for more than 30 seconds, but if I do a normal OS shutdown and leave it plugged in (but not turn off the PSU) it'll keep the settings indefinitely.

So I guess I'm asking does it only show the error if it's been unplugged or otherwise powered down completely? If not, I'd say the BIOS has been corrupted somehow.

I usually power down the system when I'm not using it, but I did unplug it recently, and it may have started doing it after that.

Contrary to popular belief, the 2032 lithium batteries found on most motherboards are not rechargeable. the draw on them is so small that they typically just last forever.