Anybody ever run into something like this?

I've got a chunk of floor in my house where if I step on the floor, a certain
section of my wall (seemingly about 4' off the floor) squeaks. Floor doesn't
squeak, just the wall. Only thing I can think of is that the floor is moving
and somehow rubbing against the wall studs. Don't know how that can be, 'tho
-- the wall plate should be on top of the subfloor, and lots of wall studs are
connected to the plate, so why would only one particular wall stud be squeaking?

I suppose I could just pull back the carpet, sink a few dozen deck screws into
the floor joist, and see if the problem goes away, but that just strikes me as
shotgunning the problem.

Any other ideas before I shotgun the problem?