The 3x revisions of the BIOS of the DZ68BC are problematic. BIOS 0028 was actually the last 'good' version. It is not possible however to downgrade from a 3x BIOS to 28. You check if downgrading to version 37 or 36 helps.
A lot of people on this forum are begging for a 'good' BIOS for the DZ68BC, but so far that doesn't seems to be a top priority.