Okay so i got cwm on the phone and I might try a wipe and reflash (after I research how). I have no idea why that would fix a usb issue but it's my last option before trying to get AT&T/Samsung to give me a new phone.
My wife's Galaxy S2 was behaving exactly as you describe. It turned out to be a dirty USB port on the phone. I used a dry toothbrush to clean the port. I also cleaned the cable end as well. Now the phone charges and works normally. I hope you got your's fixed. Cheers!