Seems likely you didn't set the option to reset the CMOS data after update. Clear the CMOS memory - with the system disconnected from the power, move the jumper on the CLR_CMOS pins adjacent to the CMOS backup battery on the mainboard from pins 1-2 to pins 2-3 for a few seconds, and return it to 1-2. That should sort out the checksum error. The BIOS settings will revert to defaults and you might want to enter the BIOS setup screen when you start the system up and set the order of boot devices and any other settings you may wish to be other than the default. In many cases all the default settings are fine.
Edited by Platypus, 29 December 2010 - 09:12 AM.