I had a similar problem and fixed it.
This is what I did. (Follow these steps):
1. Make sure your phone is not connected/plugged to your computer then continue on step 2.
(For some reason, apparently iTunes also get installed to Iphone's which makes it sort of faulty.)
2. By going to your computer's Control Panel - Uninstall itunes. To completely uninstall itunes you need to uninstall 5 programs in this very sequence. (You have to make sure you follow this in order.)
- Apple Software Update
- Apple Mobile Device Support
- Apple Application Support
3. Then simply re-install the latest iTunes. Go to http://www.apple.com/itunes/download/ , on the left side of that page you'll see a blue botton that say's "Download Now". Press that button and it should allow you to make sure that you've downloaded the latest iTunes.
4. Once you've reinstalled it go ahead and start iTunes and connect/plug your Iphone to your computer. iTunes should now be able to recognise your Iphone.
5. If it still does not work try unplugging your Iphone again, restart your computer and connect your Iphone once more. See it your computer recognises your device.
Steps 1-4 worked out real well for me so I hope it does for you too. If still a no no why not try and contact apple themselves they should be able to give help.
Got all this info with an Apple person. Cheers.