I am running Windows 8 and was running the previous version of iTunes along with support for my iPad2, iPhone4s and iPhone5. Everything was working perfectly.
Yesterday, I performed the OTA upgrade of ios7 on my iPhone5. When I connected the phone to my PC, iTunes said that I needed to upgrade to 11.1. So I did, except that it rolled back saying that it was unsuccessful and to try again. I then downloaded the standalong iTunes64 installer. The new version of iTunes installed, however the Mobile Device Support was not working. iTunes did not recognize the phone and Windows device manager showed a driver problem.
So, I then followed the instructions in http://support.apple.com/kb/HT1923 to uninstall all things Apple from my PC. I then rebooted/reinstalled. Same thing happened. I uninstalled everything a second time, and then went thru the registry searching for "apple" and "mobile device" and removed all references. This took a while. I rebooted and reinstalled once again. Same thing once more. I then extracted the files from the iTunes64 installation exe and attempted to install just the mobiledevicesupport.msi. It keeps rolling back with an unspecified error. The error code in the Windows event log is 1603.
I then unpacked the mobiledevicesupport.msi file, went to device manager and told it to find the driver, pointing it directly at the new driver files. No good, I get some "operation not supported" type message.
I am out of things to try. Any ideas would be appreciated. Thanks.