I would suggest to change the config to the USB (show hidden files and folders) and collect all the files and send them to McAfee Labs as may be some of the files are not detected and the next time you plug the USB will infect a different machine, plus they will provide you with an ED to do the cleaning in the infected machine and revert the files to the original files and make the applications works again.
Was the infected PC running an updated AntiVirus product?
There are utilities out there that will scan files and let you know if they are encrypted, possibly by cryptolocker.
I suggest only trying any new tools/software off network and only on a copy of the original files.
Good luck. Keep us posted.