Computer restarts when trying to install Zune software

[synaptikchaos]

I try to install the Zune software (the latest download from Zune.net) and when I run the .exe, it starts to extract the files and then my computer restarts.

I have XP Pro SP2 Build 2600 (32-bit), x86 processor. No spyware, no viruses, yada yada.

Things I have tried:

* Extracted the installer and ran ZuneSetup.exe inside. This results in me getting an install menu where I can get to "Preparing Your Computer...100%" and then my computer restarts.
* Uninstalled .NET framework, and then try running the installer, computer restarts.
* Removed all traces of failed Zune installs using the instructions from Microsoft Knowledgebase; ran the installer, computer restarts
* Tried using the Zune Client Software 2.5 package; computer restarts
* Disabled all my startup programs, stop antivirus & antispyware programs, etc. and tried to run installer; computer restarts

I have called Zune support. After 2.5 hours, they couldn't get me any further than where I started. I really don't know what else to try. Any ideas?

Thanks in advance.