Whenever you have a hardware resource conflict, it will more likely be an IRQ conflict rather than an i/o conflict because:
A
there are a lot more I/O addresses than IRQs.
B
the BIOS sometimes has more of a problem controlling IRQs
C
I/O addresses cannot conflict
D
software tends to correct I/O conflicts
E
software tends to mess up IRQs
Correct Answer: there are a lot more I/O addresses than IRQs.