Definately a virus, I hope you had a backup somewhere. Never connect your storage devices on other computers unless you know it is free from virus, malwares etc.
Boot to recovery mode and select command prompt under windows xp or windows vista or win 7. You can delete the malicious files if you are well verse with dos commands. Most probably there will be an inf file which is responsible for such an effect.
i found another way to solve it. by typing the command “attrib -h -r -s /s /d g:\*.*†(where g is the name of your external drive) i can access my files.. it seems my office laptop has some malware which is not detected by malwarebytes also..
you can do that but the purpose of doing so will not be served unless you do it under dos mode, where the access to other drives by the malware is fettered..
