I cannot see my iPhone when I go to 'Start > Computer', in order to transfer photos.

Under 'portable Devices' in 'Device Manager', the iPhone 'MTP USB Device' has a yellow exclamation point next to it.
The error in 'properties' is: "This device cannot start. (Code 10)". I deleted this driver & let it reinstal; without success.

I deleted everything under 'Universal Serial Bus Controllers' as mentioned in an earlier post on this forum (who had the same problem), and let the PC re-instal them on its own. This did not work.

Can anyone help?
(Running IOS6 on iPhone 3GS/Win7)