This is what happened to me thanks to the Wm5torage program, It seems to be caused by the programs messing up the default USB driver that is needed for AS...
Ive tried a few fixes myself with varying results, First try to remove the sync settings from active sync and your phone (Delete the Sync Partnership). If that is a no go, Attempt to disable the "advanced network functionality" in the "USB to PC" settings in the connection menu. If that doesent work (like it never did for me) Get out the good ole pen and paper and prepare for a hard reset (If you know what I mean)
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