Friend of mine bought a PCI USB2 expansion card. Those cards with the 4 USB ports. Problem he is having is this... When he phisically installed his new USB card in an empty PCI slot he lost his Video!! Sorry I dont know the machine spec or what the video card is or even the USB card but I thought this was very strange. He has tried it in 2 PCI slots and both times he loses his video signal?
Anyone have any explanations?
Any help would be appreciated.
Cheers...

You need to check if the problem is with the card or the motherboard. Test the USB card in another System. Likewise test the motherboard by putting a PCI card in that you know works.

he should also check with the video card manufacturers, and the motherboard manus as well, possibly a bios update might do it too, asi it may be set to ISA if its an old computer.