If you're running "other" security software but still suspect your computer is infected and want to check it with other popular tools from NOD 32, Kaspersky, F-Secure, etc, you can download and use any of the following FREE tools from these manufacturers.
1. Antivirus and Spyware removal tool from ESET - If your computer or workstation is infected with a virus, spyware, keylogger or other malware, ESET offers free malware detection and malware removal tool
2. Free Virus Removal Tools from F-Secure - Download the free F-Secure Anti-Virus for DOS (free for home use). Only the DOS version of F-Secure Anti-Virus is free.
3. Kaspersky Lab has developed free virus removal tools. You can download a free removal utility here.
4. Free Virus Removal Tools from Bitdefender – Download and use popular Bitdefender virus removal tool
5. Sophos's anti-virus solutions can remove and disinfect infections including viruses, worms and Trojan horses
6. Trend micro HijackThis - free utility which quickly scans your Windows computer to find settings that may have been changed by spyware, malware or other unwanted programs.
7. Smitfraudfix – This tool removes Desktop Hijack malware such as AdwarePunisher, AdwareSheriff, AlphaCleaner, AntiSpyCheck, Antispyware Soldier, AntiVermeans, AntiVermins, AntiVerminser, AntiVirGear, AntivirusGolden, AVGold, Awola, BraveSentry,etc
8. Dr. web - Cure your computer with the NEW CureIt
9. Malicious Software Removal Tool - The Microsoft Windows Malicious Software Removal Tool checks computers running Windows Vista, Windows XP, Windows 2000, and Windows Server 2003 for infections by specific, prevalent malicious software