Error Application not found error when acessing usb drive

Error application not found is the alert i get when i try to double click to open a usb drive. if i select the rive from the folder list in Explorer, i am able to access it. i the machine had a virus and i scanned and cleaned up the machine with mcafee and megabytes i cleaned all my usb drives and deleted the autorun file on the drives. i think this is a problem specifically with the drive leter D: because i am able to access my drive if i change the drive letter. and if i change my dvd drive letter to d: the problem starts on that drive. another issus is that im not seeing my hard drive in disk management does any one have any idea on how to reverse this with out a reload