Making some more progress, I've made another step in discovery. It's kind of a long explination, but can someone please post the quicktime.msi file?
sooooo ... are you getting a message mentioning a .msi, then a 1714, then a 1603?
if so give this a try:
Download and install the Windows Installer CleanUp utility. then use it to clear any existing
QuickTime installation configuration information from your PC:
Description of the Windows Installer CleanUp Utility
Next, we’ll manually remove leftover program files and folders.
1. On the Start menu, click My Computer (or double-click My Computer on the Desktop).
2. In My Computer, open Local Disk.
3. Open Program Files.
4. Right-click on the QuickTime folder and click Delete from the shortcut menu.
5. Navigate to C:\Windows\system32\.
6. Remove the files QuickTime.qts and QuicktimeVR.qtx.
7. Restart your computer.
once we've got all the existing QuickTime scraped away, let's try a careful standalone QT 7.1.3 reinstall.
download and save a copy of the QT 7.1.3 standalone installer to your hard drive. (we'll run the install from there rather than online.)
switch off antivirus and antispyware applications prior to the install.
Quicktime 7.1.3 Installers … get the one that doesn’t mention itunes
if that install goes through okay, does your itunes launch properly again?
(if you get an error message on the QT standalone reinstall, let us know what it says. include error message numbers if you're getting any.)