Firewire IEEE 1394 Problem

I've got a machine with an Asus P5K-E mobo. It has one built-in IEEE 1394 port on the back panel, as well as a front panel connection. Both ports appear normally in device manager. The OS is XP, SP2. When I plug in an external video capture device, it is not recognized in either port. Nothing happens at all. Doesn't matter if it's a hot plug, or if I restart, etc. If I plug the same device into another machine, no problem. Too bad I can't use that machine for my project. Any ideas? Thanks.