Probably a sticking solenoid. Mine scared me a bit the first time it did it on my 142, but I have the poor mans electrical cut off- a perfectly and regularly cleaned battery clamp just sitting on the post- no clamp action... so it was just how quick could I realize what was happening and get the hood up.

Adam- you may not realize because your computer might have it in cache or whatever (sorry Phil & other comp gurus), but your pic doesn't work.
I'd really like a pic of the 142 with 'charger, and I'd properly host it if you want... email is: iadr hotmail.com