Trojan.Qhost.WU
Trojan.Qhost.WU is a new deceptive method used to push rogue anti-spyware programs. Trojan.Qhost.WU is a malicious trojan that hijacks Google Adsense by modifying your computer's Hosts file. Once you click on the fake Google ads, you're redirected to a rogue anti-spyware website where your computer is exposed to more dangerous code being downloaded.
The best way to check on whether you're infected with Trojan.Qhost.WU is to follow this command:
Start -> Run -> cmd, add ping -t pagead2.googlesyndication.com. The results will start, for example, "Pinging pagead.l.google.com [6x.xxx.xxx.xxx] with 32 bytes of data:".
The x's represent digits. If the first digit is a 6, you're computer is not infected with Trojan.Qhost.WU. If the first digit is a 9, you're infected with Trojan.Qhost.WU.
I have found the warning message to pop up when I come home after going to music school. What I do is click the x button on this message. Of course, it then goes to the fake scan anyway. To stop it, you have to click on the x before the "scan" completes. This way, it cannot download itself. My recommendation: Be extra-vigilant when surfing the web, and never surf unprotected.