HT1926 Routine update of iTunes failed. Eventually had to uninstall and reinstall iTunes x2. Installation failed with message 'Service Apple Mobile Device failed to start. Verify that you have sufficient privileges to start system services.

When I tried to install iTunes update this failed, then tried to uninstall and reinstall itunes twice. Failed again. Could not open iTunes. I use an HP PC. Even tried to disable Macafee firewall, still itunes failed to install. Please help!!

Followed these instructions with a few changes. (Windows 7 x64)
Uninstalled programs in the following order:
- Itunes
- Apple Application Support
- Apple Software Update
- Bonjour
- Apple Mobile Device Support (uninstall failed due to Apple Mobile Device failure)***
- Restarted System
- Redownloaded Itunes from website.
- Run installer as Administratot
- Succefully installed
***To uninstall Apple Mobile Device Support
- Right clicked on Apple Mobile Device Support, Clicked Charge (second option), Repair, Next (failed to repari)
- Right clicked the Apple Mobile Device Support in the Programs and Features window and clicked Repair (third option in drop down list). (repaired successfully)
- Uninstall successful after the repair.
Below is a guess at a quicker solution:
Looking at the uninstalls, it may be worth trying to repair the Apple Mobile Device Support through the Program and Features window before trying to uninstall everything.  It may be a faster fix for the freezing service.  After the repair is successful the itunes update may work.
Hope this helps.