“Install Driver Fail/Remove Driver Fail/RollBack Error/Error 0x80070643:

Method 1:
downloading a MS program called “Windows Install Cleanup.”

Link here:

http://support.microsoft.com/kb/290301

Method 2:
I don’t recommend this to anyone just yet who is not comfortable using regedit. Make a restore point before doing this. What you need to do is go here in the registry:

HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\Installer

Then create a new DWORD value and name it:

DisableRollback

Then modify it to 1

close regedit and reboot………install the zune software

Setup will still fail but it will NOT rollback. Check and see if you have zune files or not on your system. It should be in c:\Program Files\Zune

Then you can click on zune.exe in that folder. Now mine did come back up and say there was an update to 2.1 again and went back thru the install and error out, but it’s installed and working.

After you have the software on and working, I was advised we should delete that registry key.

Method 3:
Turn on Windows Firewall. That’s it.  Try to install again.

Method 3 worked for me how retarded!