after intalling sp2 my external enclosure usb 2.0 can't be initialized, I don't know hte manufacturer, so I don't know from where to look for drivers. I also noticed that I have a usb 2.0 card, and every time I connect something to it, it tells me to connect it to a faster port, but I'm already using a USB 2.0 port!!!!!
See if you have an option in the bios for high speed/ low speed for your usb2.0. Or maybe they call it fast and ultra or something to this effect. I have never used a card, so I don''t know if you can enter the bios on that or not.
Then maybe try updating the drivers in windows. It may have "forgotten" something. Trust me, computers do forget sometimes.