I noticed about a week ago that the USB connection on my S2 no longer works. If I plug it into a PC (I've tried several xp & w7) it charges but the PC does not see it. It can't be seen in device manager and it doesn't appear like a drive like it did in the past. It also can't be seen by Kies so I can't transfer or backup files. I've tried the USB debug mode but that does nothing. Has anyone else had this issue or recommend something I can try to resolve it?