Jimgriff
this may still be pointing to a memory problem as i suggested in your previous post re office. have you tried the mem test and what were the results..
To go further, a little more info on when the blue screen of death was happening, during the BIOS checks, boot, or when windows has established, may be useful.
otherwise you may need to eliminate other hardware possibilities and run bare bones system, i.e. only mother board, memory, Hard disk and vga.
It would be very unusual for the BIOS to be suddenly out of date, to be the cause, much more likely to be a new addition of either hardware or software that then might complain that it cant be handled by the bios.
Rick