Tail lights staying on?

I have a '96 mustang gt that just started doing something strange. last night i rolled the windows up and noticed the tail lights/running lights were on afterwards. i used to have a jeep that did the same thing with headlights at times and unhooking the battery would solve the problem. Unhooked the battery on the mustang and hooked it back up and the lights stayed off... until i opened the door. On a possibly unrelated note, the dome light just started functioning normally a few days ago but wouldnt turn on before. I dont have a clue where to start checking other than the headlight switch but i dont see what that has to do with opening the door.

Seems to be in intermittent problem, parking lights wouldnt turn off again today so i pulled the headlight switch out and the lights remained on. Im not sure what that means though. most likely not the switch but im clueless to where i should look first. i looked through diagrams for tail light/park light circuits and cant see what could possibly be causing this.

Quite possibly but how can i be sure? I discovered if i pull out relay #2, from the underhood box, that the lights turn off. Isn't that just the horn relay?