I have a machine running windows xp SP3. It recently had a pretty serious virus infection. I used Combofix, Malwarebytes, Hijackthis and Microsoft Security Essentials to remove the infections. Now, when I run Combofix it scans clean, Malwarebytes (full scan) runs clean, and Hijack this shows no errors. HOWEVER, when I run Microsoft Security Essentials, I get an infection called: "Trojan: DOS/Alureon.A". Microsoft Security Essentials is not able to remove it. I've rerun Combofix and Malwarebytes, neither finds or removes it. Please help me remove this. The computer definitely acts strange (MS Word closes without warning sometimes) so I do think it's a real infection that Microsoft Security Essentials is finding.