These are the instructions I posted to another topic with this same issue.
I had this same thing happen on 2 different laptops. I finally called Apple support and they walked me through the repair. Apparently there are compatability issues with Apple software update and Internet Explorer, so if that is your default browser, you will want to download Google Chrome, Firefox or some other web browser and set it as your default. You will still be able to use IE, if you don't uninstall it, but links from e-mail will open in your new default browser, unless you copy and paste the URL into the web address line.
These are the step-by-step instructions that the tech support person walked me through. She said that it is important that you do these steps in this order.
1. Go to your Control Panel and open Programs and Features.
2. Find and uninstall iTunes from the list.
3. Find and uninstall Apple Software Update.
4. Find Apple Mobile Device Support and REPAIR this file. This is the problem child, so you must repair it first.
5. After you have repaired it, uninstall it.
6. If Apple Mobile Device Support is not removed from your program list, restart your computer and go back into the Control Panel and Programs an Features. If the file is still there, repeat Repair and then uninstall. It should now be removed from the list.
7. Restart your computer.
8. Go back into your Control Panel and Programs and Features and then find BONJOUR. Uninstall Bonjour.
9. Find Apple Application Support and uninstall it.
10. Restart your computer.
11. Upon restart, you may receive an "AppleSyncNotifier.exe - System Error" if you have iCloud attached to your account. This is normal and will be fixed when you reinstall iTunes.
12. Using Google Chrome (or Firefox or Safari) go to www.apple.com and click on iTunes and then find the button to download iTunes. It will now install properly and be usable.
13. If for some reason you are not able/allowed to change your default browser to something other than IE, then you should uncheck the box to automatically update iTunes during the install process or you may end up having to redo this fix.
Hope this helps everyone with this problem. I have now gone through this process with two of my laptops, both of them with successful results. If this does not work, I strongly urge you to contact Apple for additional assistance.