With readings that precise, I am guessing you are using a digital meter. What you are reading are mostly like ghost voltages and can be ignored.
Do yourself a favor and use a solenoidal (wiggy) tester for basic voltage checks. If you check this again with a wiggy, more than likely you will not read any voltage.
If you indeed have a drywall screw through a wire (which I doubt), you could derermine it a continuity check.
Peter
