Suddenly out of no where this WARNING YOUR COMPUTER IS INFECTED AND HAS BEEN SHUTDOWN came up on my computer screen and this free trial scan runs and then tries to get me to buy the full version of INTERNET SECURITY 2010 for 49.95 I cannot get it to go away!!!!!!!! HELP! I have ran my currant scans and they show nothing! What do I do?

Boot your PC in safe mode, and get your hands on AVG Free or Avast Anti Virus and Ad-Aware, and run the scans. Make sure they are updated, and they should find it.

What programs are you using for scanning?

This sounds like a maliciouse Malware program, I think I can help.

If the below programs do not load change their .exe file name (not the shortcut)to something like iexplorer.exe and they will work fine.

Most effective in the following order:
1. Malware bytes: http://www.malwarebytes.org/mbam-download.php

2. ComboFix: http://download.bleepingcomputer.com/sUBs/ComboFix.exe

3. SDFix: http://www.bleepingcomputer.com/files/sdfix.php

4. SmitfraudFix: http://www.bleepingcomputer.com/resources/link243.html

5. SpyBot Search and Destroy: http://www.spybotupdates.com/files/spybotsd162.exe

Also ensure you have the newest version of java as some of the old one's have vulnerabilities.
Other things to consider if you don’t already do them a third part firewall, as windows firewall only block incoming traffic, if you are infected you want something like ZoneAlarm which will block outgoing traffic also. Please ensure Windows Firewall is switched off if you install a third party firewall.

I hope this helps.

Regards,
Terry9999