Ive got the same problem in my Mk1. The boot just opens itself every now and then but then wont shut ie, you slam the boot shut but it bounces straigh back up. If i lock the car the boot then locks along with it but it soon opens again. Only happened a few times but happened on Monday and now the electrics dont work so it all has to be done manually and not through the fob or boot release.
What the hell do i do?