Today i had to install Windows 2003 R2 + SP2 (downloaded from MSDN) within a virtual machine because i needed a DC for a physical testcluster (if your not into IT, this sentence must be a pain in the ass).

I noticed that the installer just kept on going forever at the “installing devices” part.

Did you know that you can press SHIFT-F11 during setup to see that windows is doing? In this case the ‘add new hardware’ wizard was running.
You can also use SHIFT-F10 to get a command prompt

After some research i found the solution:
1) Reset the virtual machine (don’t boot from cdrom)
2) Keep the focus within the virtual machine (don’t ctrl-alt)

You’ll see it works this time, probably has something to do with the detection of keyboard and/or mouse.