A CR2032 is very (very) common (if that's what you have)
and they're good for 3-4 years and I'd replace it based upon your system's age and problems.
Once in the BIOS make sure to set the BIOS, typically Load Defaults or Load Optimized Defaults and Save and Exit = Yes.
If the problem persists then make certain that you actually Cleared CMOS properly. You'll need to unplug the PSU (power supply) for 5 minutes, then move the Clear CMOS Jumper 5+ seconds, boot into the BIOS then 'Load Defaults' and Save.
Nice video -> http://www.youtube.com/watch?v=rdHH9KrceR0