My iPhone no longer mounts in Windows. Tries to install "MTP USB Device" .. which fails When I plug my iPhone 4 into my Windows 7 Ultimate laptop, it syncs just fine with iTunes, but it no longer mounts on the desktop for me to transfer pictures and videos.

When I plug it in, Windows attempts to install a driver named "MTP USB Device" and then fails.

I've tried a number of things, the most drastic being:


Uninstall iTunes
Uninstall MTP USB Device from Device Manager
Restart
Install the latest iTunes
Restart
Run iTunes
Plug in the Phone


When I did that, Windows claimed it was installing a driver named "iPhone" (yippee!) but then it switched to "MTP USB Device" and failed again.

I've searched other forums and found strange and bizarre ideas that include exploding the iTunes MSI so I can get the Apple USB Device driver -- but that driver is installed and works just fine.
In the mist of giving you an extra idea, and to be frank I have no idea what your problem might be, let me share what I'd do to find the cause and -eventually- fix it.

You seem to have done your Windows homework well, yet results haven't been what you expected. Something I remember doing with Windows when things didn't work (in the Windows95 era this was very common!) was rebooting in Safe Mode and see if anything looked unfamiliar. 

In any case, if you still can't manage to make Windows work, before anything else, it would be interesting to make sure that the problem is not in the iPhone itself (probably nothing that an iPhone restore wouldn't fix if that's the case).

First rule of diagnosing a problem: try it on another system. The result of this simple test is going to rule out 50% of the possibilities. 

If it works, the problem is in your Windows machine and you might get better luck at Super User (since our userbase here has less Windows experience, tho we have a few geeks around). 

If it doesn't work, then the problem is not your Windows (stop removing stuff or it will go coo-coo!). 

In that case, you might want to perform a full Restore of your iPhone. I am not familiar with Windows+iPhone combo, but don't you have to Check some preference in iTunes for that "mounts on the desktop for me to transfer pictures and videos" thing to happen? I think it was called "Enable Disk's use" on iPods, but I haven't seen that option in iPhones, but then again, Maybe on Windows this is common. Forgive my ignorance in the subject.

Anyway, just make sure your iPhone mounts on another computer's desktop (with Windows) before destroying your own Windows. For what is worth, I'm not aware of any iPhone mounting on a Mac's desktop, this has got to be a Windows thing, and this is why Super User may be better suited.