CMOS/GPNV Checksum Bad (No luck with search)

Hello all,

I have been getting the CMOS/GPNV Checksum Bad error on an older Gateway computer I have (about 4 years old).

I did a search and found the recommendations regarding the battery being bad and possible bad memory. The memory is good (checked it with a module from another computer that works fine) and I just put a new battery in.

System info: Intel Pentium 4 1.80 GHz
Brand new video card (this problem was occurring before the new video card)
BIOS/Motherboard ID: PT84510A.15A.0004.P02.0112051220
512 MB RAM

This problem actually goes back over a year. We had purchased a new computer and I was updating the BIOS on the Gateway. I updated the BIOS and when I tried to reboot, I received the Checksum Bad error I indicated above. Tried troubleshooting a bit, but wasn't overly concerned because we had the new computer and, shortly after that, a new laptop. Now I want to get the Gateway working for my daughter.

I'm considering one possible cause, but I don't know if it would cause this error: I believe I downloaded the BIOS update from Intel as opposed to Gateway. I didn't realize until just about an hour ago that the 15A in the Motherboard ID indicates it's not a standard Intel set (OEM to Gateway). Could updating the BIOS with the Intel d/l instead of the Gateway d/l caused that error? If so, how do I fix it?

I downloaded the Gateway BIOS update and saved it to a thumbdrive which I created into a bootable USB device, but of course I can't boot to it to update the BIOS with the Gateway version unless I can get past this CMOS/GPNV Checksum Bad error.

I have checked all the CMOS settings and they're all good to go. I reset to default and rebooted, same problem. I did notice, however, that when I change a CMOS setting and save and exit, when I reenter the CMOS setup, the setting is changed back to default.

In any event, I apologize if this is much more info than you need, but I figured it's best to get everything you may need out now so I don't waste your time. Any help would be appreciated!

-Todd