I can spit farther than I trust the ground indicators on a surge protector, Larry.
B's given you good advice. In an old enough house, with an interesting electrical history, these impromptu grounds (if it is actually grounded) do happen, and they're really not that cool. They tend to disappear as abruptly as they appeared, usually at
just the wrong time
If you're not too comfortable / experienced with house wiring, I'd shell out the cash for a quick electrician's visit as well ...