I have seen a locking program like that, the program installer came from the USB Drive's package. but it can be bypass.. so its no use. somehow, you need a program that autoruns to halt or temporary disable the window's functions to access that usb drive and enables when prompted with password.. the encryption part, i dont think its good. and the program will act like a virus coz it changes some explorer security. maybe fodder is right. but is possible

I had an Acer P223w and its good..

how it will help? the file attached, when activated, is used to delete the autorun.inf when it is detected, it also watches the wscript issues(its not mine btw). it doesn't delete the main virus or the script but it will prevent the execution of the USB virus. it is attention to common USB virus solution, not an all-around file antivirus.

intentionally, i want to provide an idea. it is better if we look forward to "solutions" rather on something else. if it is not clear yet, i just want to ask a question: is it worth doing this or not? so we can close this topic and proceed to better ones out there  :(