PS/2 mouse doesn't work with iPod plugged in
One of my friends is having a problem with her computer, which I'm trying to help with. Her mouse connects to the PS/2 port, and she's discovered that it doesn't work if she boots up with her iPod Shuffle plugged into the USB port. If she sticks it in once the computer is already booted up, everything is fine. She's running Windows XP Professional.
Obviously this isn't a huge problem, but I'm a little curious as to what might be causing it. I built the computer, and it's possible that the USB port isn't wired to the mobo perfectly - is it possible for some of the wires to be connected wrong, causing it to function okay but with glitches? Or is it a works-or-doesn't situation?