Corsa did this to me about 18 months ago, towards the end of a week of nights where all I'd used it for was 3 miles into work and 3 miles home again. Just not enough time (7-8 min drive) to get the start effort back in the battery. An eight hour charge did the trick and (touch wood) not had a problem since, though usually on nights I try and drive home the long way round at least a couple of times to boost the battery a bit.
Think I posted on here at the time and the feedback was, with immobilser and CDL engaged there is a constant trickle from the battery. Maybe it's time car designers started to fit two batteries - one purely for the start and the other to feed all the other equipment.