I can't re install iTunes on Windows Vista- itunes error 7/Windows error 5.

I have updated my computer with Service Pack 1 & 2 for Windows Vista. For some reason Itunes was deleted and when I try to reinstall it I get a message "iTunes was not installed correctly. Error 7, Windows error 5" I have done the following to try and remedy this problem:

1. Delete all Apple software (to start over and reinstall) - I cannot delete Apple Application Support (Access Denied)

2. Repair itunes - Same message

3. Logged on as Administrator and tried to take ownership of the file that denied permission - Access Denied

4. Tried to install MS .NET Framework 3.5 & 4.0: 3.5 was succesful but 4.0 was not - something went wrong in the installation.

Please help! 😟