Fuse #15 madness. HELLLLP!!!

Literally out of the blue the "R" has developed an appetite for 10A fuses in the #15 spot.

It blows about 1 second after the the car is started and takes out my gauges, seatbelts, sunroof, windows *and* the A/C control unit! (I would'nt mind the former, but for the windows and HVAC, it's been hovering in the high 90's all summer, so I gotta figure this out ASAP!).

Anybody privy to knowledge about common (or not-so-common) gremlins on these circuits? I've looked in my shop manuals, but I have no idea where to start, and tearing the dash out and hunting down a short in largest harness in the car does *not* sound like much fun to me...