Trying to install the RTM version of Windows 8 Pro onto my desktop via upgrade. It's now been over an hour and it is still stuck at 20%. Any idea what is going on?
What Media you use for to "upgrade", DVD or USB? Have you compare the Checksum of the file you downloaded?
I had that on one of the beta builds, it was either the Intel CPU's on-board IGPU or Hyperthreading as I disabled both and enabled again once installation went fine. RTM had no such issue though.