"A newer version of QuickTime is already installed. This installation cannon proceed while the newer version of QuickTime is installed."
That one is usually trouble with the QuickTime.msi for your current installation of QuickTime.
Unfortunately, these sorts of msi-related troubles have gotten more complicated to deal with ever since Microsoft pulled the Windows Installer CleanUp utility from their Download Center on June 25. First we have to find a copy of the utility.
Let's try Googling. (Best not to use Bing, I think.) Look for a working download site for at least version 3.0 of the Windows Installer CleanUp utility. After downloading the utility installer file (msicuu2.exe), scan the file for malware, just in case. (I use the free version of Malwarebytes AntiMalware to do single-file scans for that.)
If the file is clean, to install the utility, doubleclick the msicuu2.exe file you've downloaded.
Now run the utility ("Start > All Programs > Windows Install Clean Up"). In the list of programs that appears in CleanUp, select any
QuickTime entries and click "Remove".
Quit out of CleanUp, restart the PC and try installing iTunes again. Does the install go through properly this time?
(If you do find a clean download site for the correct version of CleanUp, please don't tell me where it is. Without wishing to sound paranoid (although I grant it does sound paranoid), there is a non-zero chance that posting links to download locations for the utility here at Discussions leads to that download location being shut down.)
