No more fax, modem booted by firewire card

Please help.

Ever since I installed a firewire/USB2.0 PCI card, my modem PCI card
disappeared from system (Windows XP pro, P4), now they can NOT exist in one
system any more, if I have both PCI cards in the system, the system will
stall at start up, the famous "blue screen of death" show up. If I get
either one out, the remaining one will function normally.

I believe there is a conflict between those two cards, question is: how to
solve it?

Thanks,

LEO