Well I know that there is a certain virus called Win32.Virut.A-Q Which infect all of your computers .exe and .scr files, which makes that msg pop up when you try to open them. I doubt you've got it, but it's happened to me and that's the message I got too.
Btw, does it only happen with hacks or alot of your files and programs?
EDIT: Sorry I only just read that it only happens on hacks.