Computer won't detect Iphone!

I'm having an issue with one of my iPhone 3gs phones.

One of my iPhones will connect to the computer just fine (charges, itunes detects it, etc).

When I plug in my other phone, the computer nor itunes detects the phone. If I plug the phone into the wall charger the phone will charge.

I've done quite a bit of googling and I've tried many things such as

1. Uninstalling/Reinstalling iTunes
2. Erasing Sync History
3. Trying different cables
4. Trying different USB ports
5. Pressing the Power and Home button and getting to the "restore point"
6. Making sure I have at least one photo in my camera roll (so that hopefully the computer will at least detect it)
6. Making sure the Mobile Device and Ipod control are turned on in the services list.

I've tried some other things but no matter what I do this iPhone will no longer be detected by any computer (I've tried 2 computers and all the possible ports / cables I have).

I have an ipad 2, 2 iphone 3g's phones, and an ipod and all of them seem to work normally except for the one Iphone.

Is there some trick I can do to get this thing up and running again or do I need to bring it to an Iphone fix place? I doubt apple would help me with this issue so I figured I'd try a 3rd party forum avenue, aka, this place!

Thanks!

Try step 8 here:

http://www.everythingicafe.com/foru...one-ipod-ipad-not-recognized-in-itunes.78777/