If you iPhone is recognized by the system, Windows, but not iTunes or you're getting "An iPhone has been detected, but it could not be identified properly", try this:

Unplug your iPhone. Go to Start > Right click on Computer > Click on Manage Click on Services and Applications. In the list, find Apple Mobile Device. Right click and select Restart. Next, look for iPod Service and repeat this step. Right click the service and select Restart. Replug your iPhone and it should appear in iTunes.

If iTunes still does not see your iPhone... here are some more tips.
Leave the iPhone plugged in. Goto Start and right click on My Computer in XP or Computer in Vista. Click on manage. Click on Device Manager.  Look for "Portable Devices" There should be something in there about Apple iPhone. Right click it and select "Uninstall" Look under "Universal Serial Bus Controllers" and find Apple Mobile device USB controller. Righ click it and select uninstall. Disconnect the sync cable and repeat the first steps in section 1.

If it still doesn't work... try this :
Repeat the two steps above, and leave the iDevice unplugged. Disconnect everything usb and network related on the computer,(Ethernet or WIFI. Turn off your WIFI if you have to.)  except for the Mouse (If it's even usb) Start Itunes and let it load. Reconnect the iDevice and it should work.

If it STILL doesn't work... try this:

Apple has known about this problem for some time and has done nothing to fix it... I found posts from people from 07 complaining about this. Try calling them and complaining. They'll tell you it's the virus scanner or something like that but the bottom line is, it's their software!!!

It's a yPhone, for "WHY THE FU(K DID I BUY THIS PIECE OF $HIT?!?!"