QuickTime update error

Question

I am trying to upgrade QuickTime/iTunes on my mother's XP PC. Each time I run the installer, it throws an error when updating QuickTime:
"The feature you are tying to use is on a network resource that is unavailable. Click OK to try again or enter an alternate path to a folder containing the installation package 'QuickTime.msi' in the box below."
I searched for this file but cannot find it. The machine I am trying to update is not networked with any external drives or other machines, so I have no idea why QT (or Windows) thinks this file is on a 'network resource.'
When I click 'OK' to try again, I get the following message:
"The path 'C:DOCUME~1\Dotty\LOCALS~1\Temp\_is5D3\QuickTime.msi' cannot be found. Verify that you have access to this location and try again, or try to find the installation package 'QuickTime.msi' in a folder from which you can install the product QuickTime."
The 'Dotty' in that path is my mother's account name on the machine.
I have tied uninstalling QT and iTunes and searching and removing files that look like they would be used by QT or iTunes, but still no luck.
We bought her a new iPod for Mother's Day, and she hasn't been able to use it yet (because it required that she upgrade from iTunes 6 to 7).
Any help would be appreciated.

Answer 1

"The feature you are tying to use is on a network resource that is unavailable. Click OK to try again or enter an alternate path to a folder containing the installation package 'QuickTime.msi' in the box below."
let's first try the following procedure with that one.
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.
now try another itunes install. does it go through properly this time?