Here's a good one. Had some snapped studs in the exhaust manifolds which obviously sounded rubbish and lead to the engine warning light coming on due to air leaks. Repaired the leaks (what a job!) and borrowed the code reader from work to reset the light. It read the code alright but when I hit the button to clear it I heard a definate click from behind the dash and it was like I had cycled the 12v off and on again. The trip meter reset to zero, I lost all the presets on the radio and it took a good minute before I was able to start the engine.
It all seems to have recovered and using the same reader on other cars has never resulted in anything quite so drastic. I love italian electrics!