the closet light coincidence is really bugging me. in theory, it should have zero effect seeing how it's not tied to the HT circuit. current travels in the direction of least resistance. electrons WANT to find ground. that is why I do not think a separate circuit could affect this as any odd voltage / stray current will seek ground through that neutral buss.
whatever is causing this phenomena, it is common throughout the home, so it would be at the main distribution point. when thinking about this, I believe your main feed MAY have an improperly grounded meter base / service panel. it wouldn't hurt for you take a look at that with a VOM (volt/ohm meter).
just out of curiosity, does this static go away when you turn on any other light? or is it only with this closet light?
