mainsv.exe is a Trojan.Tompai-B. mainsv.exe opens a back door. mainsv.exe tries to terminate antiviral programs installed on a user computer. Related files: %Windows%\mapserver.exe %System%\mainsv.exe More info: http://www.sophos.com/virusinfo/analyses... Removal: Kill mainsv.exe process and remove mainsv.exe from Windows startup using antivirus (also check How To Remove section)Startup Optimizer.