Dead battery, any ideas why?

[motoadve]

Base Boxster 05 Trip.
8,000 Miles.

Never had any signs of problems, and the last time I drove the car was Friday.

Today totally dead battery, no horn, door lights nothing at all.
Im charging it right now.
Any ideas why this could have happened?

I didnt leave lights on, or radio on, or keys on.

[racer_d]

Lack of use? c'mon.. 2-3 year old car with only 8k miles? (depending on production date the battery could be 3 years old, not really too old but, like most things, they last better if used )Have you ever checked the battery level? How much charge is the battery taking?