the jaffa

I have also replaced the battery with a new one as I mentioned above.

I think my BIOS may be corrupt. Basically I've been getting the BSOD recently, so I decided to drop my clock speed down in the BIOS to it's default speed (my PC has been overclocked for about a year now without any problems). After having done so, the PC will now not boot up. I have reset the BIOS via the jumper pin and by removing the CMOS battery (I have also replaced the battery with a new one) but it will not boot up. It posts sometimes (and sometimes not) and then says "CMOS Checksum Error, Defaults loaded press F1 to continue or DEL to enter BIOS." Problem is, which ever button I press, nothing happens - I can sometimes get it to enter the BIOS but instead of the BIOS screen I get a cursor in the top left corner of a blank screen. :/ If any of you can help me, please don't use too many technical terms, I don't know a great deal about PC's. I have a Gigabyte Ga-8n-sli motherboard (I don't know which BIOS version I have, I've never changed it) and Windows XP sp3. Thanks Father Ted Crilley.