Ive had my MBA for several months now - its always been fine - spot on, and Ive been very happy with it. However, today I experienced an issue, which I hope is a one off! My laptop had around 35% battery life remaining. The system was used to browse the net and check my email. All applications were then closed and I then closed the lid to put the system to sleep. When I went to use the system a few hours later, I noticed the system was very hot to the touch. The battery was also completely dead. Nothing running in the background at all. What could have caused this??