Please help! Mouse/kb lockups on sewers->cave->office transition map

I believe the root of the problem is my PCI express preventing my PCI slot from working when the graphics card is under stress. What kind of stress, I'm not sure, perhaps memory since it only happens on maps with transitions from tileset to tileset, and only when near the transition point.

You see, my USBs on my motherboard burnt out, I have the PC display on my TV, so cords are out of the question, and I have to use a PCI USB card.

I've tried all sorts of settings, changing the PCI slot, checking for conflicts, updating drivers for everything.

I'm hoping someone has had an issue at least similar, and some sort of possible response. Turning graphics settings to minimum does nothing.

The card is a gtx260.

Any help is welcome, before I have to start spending cash.