I have this same problem. I was driving down the road and I used my blinker when I changed lanes and my door locks started locking and unlocking and my ISP went CRAZY. freaked me out something fierce because I was going 80 on I95. I checked my batter terminals and found a shit load of corrosion on the negative terminal so I cleaned it with COKE and I have only experienced it once since then. I think I need to replace my Ground cable. It's weird because I always thought the Ground cable was terminated on the frame of the vehicle but mine is terminated on the alternator.
one more thing. Where is the 175 amp Mega fuse located?