I can totally understand the sceptisism, but for the record its not my house- I was working there moving some stuff out.
Never experienced anything before and I hope I don't again, it's best to try and work the whole thing out (open window etc etc) but looking back on it in the cold light of day it's more interesting than scary.
It's kinda cool from a scientific angle, just because we don't understand something doesn't mean we should totally dismiss it.