One of the ways by which a virus can infect your PC is through USB/Flash drives. Common viruses such as 'Ravmon' , 'New Folder.exe', 'Orkut is banned' etc are spreading through USB drive . Most anti virus programs are unable to detect them and even if they do, in most cases they are unable to delete the file, only quarantine it. Here are the things which you can do if you want to remove such viruses from your USB drives or harddisk. Whenever you plug a USB DRIVE in your system, a window will appear similar to the one shown below…
Don't click on Ok , just choose 'Cancel'. Open the Command Prompt by typing 'cmd' in the run box. In the command prompt type the drive letter: and press enter . Now type dir /w/a and press enter.
This will display a list of the files in the Flash drive or Hardisk. Check whether the following files are there or not
Autorun.inf
Ravmon.exe
New Folder.exe
svchost.exe
Heap41a
or any other .exe which may be suspicious.
If any of the above files are there, then probably the USB drive is infected. In command prompt type attrib -r -a -s -h *.* and press enter. This will remove the Read Only, Archive, System and hidden file attribute from all the files. Now just delete the files using the command del filename. example del Ravmon.exe. Delete all the files that are suspicious. To be on a safer side, just scan the USB drive with a latest anti-virus program like McAfee or TrendMicro's PCCillin to check whether it is free of virus or not. Now remove the drive and plug it again. In most of the cases, the real culprit turns out to be the "Autorun.inf" file which mostly gets executed when someone clicks Ok in the dialog window which appears above. Thus the infections can spread.