Hello, Malwarebytes and viruskiller, I, also, have had my COMMAND.COM flagged as having Trojan.Agent. I, also, am running MBAM 1.46 with updated virus defs (913051804). My COMMAND.COM is freshly expanded from a genuine MS XP Home CD. Weirdly, right-clicking in Explorer and choosing scan with MBAM from the context menu says it's clean. Start/Run mbam.exe /developer c:\windows\system32\command.com runs a quick scan which says it's clean. Start/Run mbam.exe /developer runs a full scan which says Malwarebytes' Anti-Malware 1.46 www.malwarebytes.org Database version: 913051804 Windows 5.1.2600 Service Pack 3 Internet Explorer 8.0.6001.18702 5/18/2013 9:50:01 AM mbam-log-2013-05-18 (09-50-01).txt Scan type: Full scan (C:\|) Objects scanned: 340130 Time elapsed: 1 hour(s), 0 minute(s), 32 second(s) Memory Processes Infected: 0 Memory Modules Infected: 0 Registry Keys Infected: 0 Registry Values Infected: 0 Registry Data Items Infected: 0 Folders Infected: 0 Files Infected: 1 ... Files Infected: C:\WINDOWS\system32\command.com (Trojan.Agent) -> No action taken. [27517B842938D5006908C61D87F3AB7C] So, quick scan didn't flag it, full scan immediately afterward did. (The machine was disconnected from the net at the time.) I'll try updating the MBAM engine as recommended. If I still have the issue, I'll add another post. BTW, thanks, MBAM is excellent. I have recommended it to many friends.