ASUS P5K Deluxe - Intel P35 Bearlake + E6600 B1 / Q6600 B3

[msgclb]

My P5K Deluxe has developed a major problem. I updated the BIOS from 0304 to 0307 but it failed with this error:

CMOS Checksum Bad

I've tried to flash back to 0304 and also 0123 that's on the DVD. Each time when I boot it stops on the boot screen with the above error.

I used ASUS EZ Flash 2 with a USB stick or the DVD. I've tried both BIOS versions several times.

Update:
I checked the online site where I bought this motherboard and the replace/repair RMA process looks like the route I'll take unless someone has a suggestion to fix this problem.

Update #2:
I tried the ASUS CrashFree BIOS 3 Utility using both the support DVD and my USB flash drive by copying the BIOS file from the support DVD. They both updated the BIOS but I still got the same error.