When the computer is infected by Malware and it prevents to execute or install Anti-virus program, use Malwarebytes Cameleon to scan the computer without interrupting by Malware.
Download: http://www.malwarebytes.org/chameleon/
How to Use:
1. Download Malwarebytes Chameleon
2. Extract downloaded zip file
3. Execute svchost.exe with Administrator permission.
4. The program will start installing driver, Anti-Malware and run abam-setup.
5. Then the program will kill known malicious processes. This task takes up to 10 minutes. Need to be patient.
6. Perform a Quick scan.
7. Click Show Results
8. Check all found malwares and click “Remove Selected”
9. After rebooting, please do full scan to find hidden malwares.
Reference: http://malwaretips.com/blogs/smart-guard-protection-removal/
Reference: http://www.techrepublic.com/blog/it-security/rootkit-coders-beware-malwarebytes-is-in-hot-pursuit/