I learned from fellow MVP, Donna Buenaventura, that Symantec has identified as Trojan.Kardphisher. The Trojan is installed when the PC is restarted. A window appears that has been designed to look like the Windows Genuine Advantage (WGA) Activation Form.
There are two options presented on the form -- activate now or later. According to Symantec, it isn't possible to run Task Manager or any other applications. Choosing no results in immediate shutdown of the computer. Selecting yes presents an activation window, but not quite what is provided by Microsoft.
The trojan window requests credit card information. Microsoft does NOT request credit card information for WGA Activation. Do not be tricked into providing credit card information. Instead, update your antivirus software and run a full system scan. If you need assistance, visit one of the ASAP Member Sites.