I'm assuming you haven't made any recent hardware changes to your system but I had to ask.
I terms of BIOS, have you checked to see if there is any setting related to your floppy that looks strange (can't think of any such thing off the top of my head).
Maybe restoring defaults (assuming that won't cause any issues w/ manual confg you've done in BIOS for your hardware) would be a good next step.
'BIOS rom checksum error' sounds like BIOS isn't happy w/ itself @ the instruction level or config level. A BIOS flash may be in order, check your vendor.