Parallels Tools Installer Hang

I have several Windows XP VMs, and Parallels Tools installation has always been a problem in just one of them. This is a VM I imported from an old Sony Vaio laptop.

Looking at the installer log (C:\WINDOWS\Temp\parallels-tools-setup.log), the install was hanging at this step:
DIFXAPP: INFO: ENTER UpdateDriverForPlugAndPlayDevices…

The first thing to cross my mind was a couple of Bluetooth drivers that came over from the Vaio. There is no bluetooth device in the VM, but I never uninstalled the drivers before because I had no evidence that they were any sort of problem. If it ain't broke …

Anyway, I went into the Device Manager (left click on "My Computer" on the desktop, select "Manage", and then find "Device Manager" under "System Tools") and uninstalled the Bluetooth drivers.

But then, in the driver list, I noticed that under "System Devices" there was a thing called "Parallels Tool Device". The version number was 5.0.9310, which is the version I was upgrading FROM. So, I uninstalled that driver as well, and rebooted.

On restart, the Found Hardware Wizard popped up, wondering where the Parallels Tools device driver was. I dismissed that, and proceeded with installing Parallels Tools.

And then a miracle occurred: the Parallels Tools install went through perfectly.

I don't know whether the problem was the bluetooth drivers or the Parallels Tool driver. Moral: never change two things at once, because you won't know which one was the problem.

However, for anybody else who is having problems with the Parallels Tools installer hanging - you might try uninstalling the Parallels Tools device and see if that helps. If not, look around for other unnecessary device drivers.

Good luck
-Rick