(Fake) messages from microsoft

[jholthaus]

We are getting written and spoken message (saying it is a critical alert from Microsoft) with a foreign accent saying that our computer is infected with pornographic spyware and riskware and our credit card, financial data, Facebook and email logins will all be compromised if we close our computer and don't call an 888 number within 5 minutes. we have run our virus scanner twice, but can't seem to get rid of the message flashing on the screen.
we've had similar messages in the past and have gotten rid of them by shutting down the computer and/or running the scanner.

[bakertaylor28]

Rather, this is because they're using JavaScript to keep you from closing the browser. (assuming this is going on in the web browser).
The quick fix is to Ctrl+Alt+Del, bring up the task manager, and kill the browser and related processes.