When I first got my curve 8310 from AT&T I installed the software on my pc and for several weeks everything worked fine, now suddenly I receive a "usb device unknown" error. I've tried uninstalling the software, removing the battery, everything else I could think of. The dork at AT&T is no help neither is their web support. Now when I plug my phone to my pc after receiving the error, the media manager shows no device connected, when I try the find your device option it finds nothing. The device manager on my pc shows "unknown device" plugged into the usb. I also tried every usb port on my pc. can anyone help me?