I had a problem with my Interstate when it was new. Turned out to be that one of the screws on the battery was loose and was only making intermitant contact with the battery.(it's covered so you can't see it) I ended up stuffing some paper behind the nut and then tightened it. Now all is well. It may appear as if the screws are in, but check the back to make sure the nuts haven't been pushed back to a point where the screw wont grab the threads.