Hi, Rob-h
Try the following
(1) bad RAM sticks. Check each stick 1 at a time, in each slot and then clear the cmos.
(2) Read your motherboard manual
(3) replace the battery on the motherboard? This is the usual cause for "checksum" errors
(4) Download the iso file for Memtest and burn it onto a CD/floppy. Boot from it and test the RAM.

regards