Click on the below link and download the file "AutorunExterminator"
Extract it --> Double-click on "AutorunExterminator" -
This will remove the autorun virus from the drives.
For xp ,go to run and type
cmd and click ok
For vista and 7
Go to start and type
Now right click on it and select run as administrator
Now run this command
attrib -h -r -s /s /d g:\*.*
where g refers to your external hard drive letter
Let me know how it works