|application not found' means it is trying to run a program from the memory stick. Usually a virus. When the host computer is fixed this error comes up. Make a folder (FOLDER) not a file on every flash drive you have called autorun.inf.|
If it complains then you have a file called autorun.inf and it contains some commands. See those commands for what this issue is.
A restore point might bring back the virus so check the drives first.
Hang up and live.