Activation issue with the Windows RT 8.1 Preview. Microsoft Support released a script to fix the issue. (download from my OneDrive below). The issue should also be fixed in a newer update, so running Windows Update may also fix the issue.
1. Please save the attached ZIP file (RTactivation.ZIP) to your Surface.
2. Browse to the location of where the ZIP file is saved (the Downloads folder by default).
3. Right click (or tap and hold) on the ZIP file and select Extract. By default this will create a new folder with the same name as zipped file.
4. Inside the new folder is a file named RTactivation.cmd – it will have what looks like a gear as its icon. Right click (or tap and hold) on the file and select Run as Administrator.
You will see your Surface switch to the Desktop and a black command window open up. The script will automatically run a series of commands, so you will see text appear in the window, a pause, then more text, then a pause, etc. Just let the script run until the script completes and the black command window closes automatically.
After the script completes, restart your Surface and when Surface connects to the internet, activation should be fixed
Orginal Thread Here – Thanks to member: SeeVuPlay