According to the Windows installer error messages, this is a file not found error.
http://msdn.microsoft.com/en-us/library/aa372835.aspx
If I understand correctly, this happens when you try to uninstall with Add/remove programs?
Do you have a working iTunes now? What I am going to suggest is a manual removal and installer cleanup. You will not have a working iTunes if the install part doesn't work.
== uninstall with cleanup and reinstall ==
Download a fresh copy of iTunes and the stand alone version of Quicktime
http://www.apple.com/quicktime/download/win.html
http://www.apple.com/itunes/download/
Download and install Microsoft Installer cleanup utility, there are instructions on the page as well as the download. Note that what you download is the installer not the program – you have to run it to install the program
http://support.microsoft.com/kb/290301/
Now use the following method to remove iTunes and its components:
XP
http://support.apple.com/kb/HT1925
Vista
http://support.apple.com/kb/HT1923
If you hit a problem with one of the uninstalls don't worry, carry on with the deleting of files and folders as directed in the method.
When you get to deleting Quicktime files in the system32 folder as advised in the method, you can delete and file or folder called Quicktime.
Restart your PC.
Run the Microsoft Installer Cleanup Utility. (Start > All Programs > Windows Install Clean Up)
Remove any references you find to the programs you removed - strictly speaking you only need to worry about those programs where the uninstall failed.
restart your PC
Install the stand alone Quicktime and check that it works.
If it does, install iTunes.
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