BAT.Clouner is a member of a huge BAT-trojans' family. It is common for this pest (and other batch-file infectors) to search for BAT-files on the infected PC and infect them by overwriting their original content with a copy of infection. This technique usually leads to different system problems, because several BAT-files (like autoexec.bat) are tremendously important for the proper system working
BAT/Clouner