Short circuit on motherboard perhaps?

Here’s a curious one. I built a system back in July with a Tyan Trinity 400 S1854 mobo, Celeron 533 CPU for a client, which has been running fine until recently. Now it doesn’t power on the video display and complete the boot process unless the keyboard is unplugged first – no matter which keyboard we try.

A colleague who looked at the system in my absence is suggesting a possible short circuit on the keyboard port of the motherboard. I’m going to take a look at it next week to see if it hasany signs of shorting, but wondered if anyone here might have any further suggestion I haven’t considered. We’re still way under warranty for the motherboard so I have no problem with having it replaced if needed.

Any ideas?