Any idea why IEUser keeps getting logged off every minute?

I downloaded and unpacked the RAR files for IE9/Win7 without any problems. I then loaded the unpacked files into Virtual PC. That all started up fine. I then logged in as IEUser using the password in the instructions PDF.

The desktop loads fine and I can start IE without problem. After one minute, however, I get presented with the login screen (as if I'd pressed Windows+L).