I have been having the same problem for some time: phone connected always charges but alternates between a complete non-recognition in Windows7 (no beep, no new hardware notification) or an announcement that the device has malfunctioned and so was not recognized and a callup of an unknown usb. I have tried various strategies-- playing with the usb settings among all three options; downloading new device drivers from kies mini, even doing a hard reset to factory settings, which required reinstalling my contacts and calendar afterward. Still nothing-- on three separate computers, all recent, high-end machines, two running Windows7 64 bit, the third running Vista. The US Cellular rep at the store was no help. I have used different cables, and different usb inputs-- front and back of the computer. Any help will be greatly appreciated.