you probably need to replace your bios battery...look at your motherboard and find/remove the battery...bring it to cvs and buy a replacement...the one you currently have must have gone bad or been flakey to begin with. The batery looks like a huge watch battery.
It is also possible that your bios is misreading the voltage of your battery...in this case you may get this error even with the new battery. You could enter the bios and set it to Halt on no errors. This setting could be in a variety of places depending on the motherboard you have.
If it isn't a P6 then it isn't a processor
110% BX fanboy