error 1506

Try manually removing all quicktime and iTunes files. You may want to use the Windows Installer Cleanup, http://support.microsoft.com/default.aspx?scid=kb;en-us;290301

You got Rid of all quicktime files and references?

to Verify That All QUICKTIME Files Are Removed
Go to: Start/Find/Files or Folders.


Enter QuickTime as one word in the Name box.


Click Find Now (be sure you are in the C drive of your computer).


Confirm that the following files are NOT on your computer. If they are still on your computer, delete them.


QuickTimeInstaller.ini


QuickTimeInstaller.exe


QuickTimeInstallCache.qdat


then reboot your computer
OR
Close the program tray icon (lower right corner of taskbar) before trying to remove (or installing standalone)? ( or ctrl alt del and close these first: iTunesHelper.exe, qttask.exe)

or:
Start - Run - copy and paste this into the run box:

C:\WINDOWS\unvise32qt.exe C:\WINDOWS\System32\QuickTime\Uninstall.log


(check to see if there is a file "uninstall.log" in the C:\WINDOWS\System32\QuickTime folder)

last resort (since you cant get rid of it anyway) -
delete c:\program files\quicktime folder and c:\windows\system32\quicktime folder
run regedit - delete these keys:
HKEY LOCALMACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Quic kTime
HKEY LOCALMACHINE\SOFTWARE\Apple Computer, Inc.\QuickTime