Originally Posted by Xopher
At the "Where do you want to install Windows?" screen hit Shift+F10 to bring up a command prompt.
Type "diskpart" and hit enter.
Type "list disk" and hit enter.
Type "select disk x" replacing x with the number of the disk you want to install Windows to.(Typically you will see a * under GPT for the disk you are having a problem installing to.)
Type "clean" and hit enter. (SEE NOTE BELOW!!!!!)
Type "exit" and hit enter.
Close the command prompt window.
Click Refresh in the "Where do you want to install Windows?" screen.
You should now be able to install windows on the disk that was GPT formatted.
***NOTE*** The clean command will destroy ALL data on the disk you run it on!!! This includes any OEM specific hidden recovery partitions etc. Be absolutely SURE there is NOTHING you need to keep on that disk before running any of these commands. Also this typically converts the disk from GPT back to MBR, you may alternativly use the convert command in diskpart. To read the help in diskpart, type "help commandnamehere" for more info...