I had a problem once with my radio being constantly on, even when the car was turned off. Turns out it was because of the fuse that looked good, but it wasn't. It was the older metal kind of fuse, pitted over the years, though all in once piece. A mechanic told me to get rid of all of them, replace them with the new copper ones. Resistance on one fuse can cause other unrelated problems. To replace them all is only like, $8, so do them all.

jeff 1991 300d, 105k