I bought PCI USB2.0 Card (Vivanco NEC) to my Pegasos, but when I install it to my computer it caused operating system is not booting... I see only a black screan.
then swap it, the firmware doesn't work with it. same with my old card. You can also try the usb-enable? (or similar) option in firmware, i didn't know this option... so if it's there enabled, try to disable it, and install the card again...