Ok. I can now assume the Trendnet DVI switcher combined with NVidia GTX 260 is causing this issue. I am only using the DVI cable (not usb) between Trendnet and NVidia card.

There's a very interesting read over at http://forum.tcelectronic.com/viewtopic.php?id=3479 regarding NVidia cards searching the HDMI port. The third page provides enlightening information.

I don't have an HDMI port, but perhaps the issue is related. Something about the DVI switcher being connected is interfering with the PCI Firewire Cards and Mobo Firewire Bus or Eventide Driver. I'm interested in the free DPC spike tool they provide.

My H8000FW is now working without the KVM switch.