I want to take a system disk out of one machine, Celeron 800MHz, m/b of unknown lineage (AMIBIOS circa 1999) and swap it into a Celeron 2.4GHz, ASUS m/b, P4S800-MX (ASUSTeK bios). On doing so I get the dreaded "STOP 0x7B" message which, I believe, means the new system cannot read the MBR. I thought MBRs would have been fairly standard across systems of basically the same architecture. Swapping the disk back to the old system and all is still OK. Any thoughts on fixing this sort of problem apart from a complete rebuild of the system?