@dyn!o:
According to the Intel and AMD manuals, the DEC instruction can cause several exceptions, but only when working with memory addresses. There are no defined exceptions when working with registers.

Please can you give us an example how a "DEC reg8/reg16/reg32" instruction can cause any exception or do anything else than decrementing (or incrementing when a register underflow occurs) the register? (and please don't come with breakpoints or the trap flag since they are no result of the DEC instruction as such)