plugging device and unplugging, then plugging in again (is the procedure used when moving a computer) occasionally throws windows for a loop and what worked before glitches out. I would suggest that you go to Device Mgr, uninstall the firewire port (1394 controller), then cold reboot the computer (shut it down, then boot it back up). Windows should find the 'new hardware' and reinstall the drivers for it again from its database, using the drivers in the INF folder that your system originally used in case you used the ones from your motherboard cd. Then try your capture program again, making sure it is set/configured for firewire and not USB.
I can't capture video using firewire from my Sony DCRTRV50. I'm running XP Pro with SP2 on an ABIT IC7-G. Device manager says that the 1394 controller is working properly. The camcorder shows DV in when the firewire cable is inserted, attached to the firewire port on the PC. I've tried the other firewire port and another firewire cable - no joy. The camcorder isn't recognised either from Premiere Pro or Windows movie maker. This setup worked fine before I moved the machine to another room. I hope someone can help.