Upgrading to Ultimate - Hang at 18%

I ran the Windows 7 Ultimate installation on my 64-bit Intel machine with Windows Vista. The installation goes through the process just fine, until it is at 18% of "Expanding Windows files". It never gets past this point. Below it shows "Windows needs to restart your computer", but it never does. Also, the system is completely locked up at this point. I tried pressing the start key to see if the system responds and the system locks after it opens up.

I do have a system with raid and intel i7 cpu. Overything is normal besides that.

Any ideas?

Thank you.

Thank you Adrian. I tried the process again, but now decided to let the installer sit at the 18% mark for a while. I didn't touch any buttons this time and it eventually came through.