OK, now that everyone has commented on your sex life we should get to your original question.
I've been in IT most of my adult life and I've never heard the statement that "a screw missing means someone copied my hard drive". In fact, a good IT person can copy your hard drive by simply turning on your laptop and plugging in a USB drive with the right software. Easier and faster.
Maybe the screw (can I say that now? ) simply fell out and housekeeping saw it. I wouldn't jump to a Mission Impossible scenario just yet.