Mine is exactly the same at the moment! (it's only 2.5 years old) last week we went out and came home to find it ticking really loudly and the light was flicking on and off, after an hour or 2 it decided to turn itself off completely and then a few hours later it randomly turned itself back on, it has repeated this pattern for the last few days.
I've been looking on the internet for a solution and found this link to somebody else who had the problem and 2 people suggested the new electronic card, I'm debating whether to buy one to try to fix it
http://www.howtomendit.com/answers.php?id=170554
Sophie
February 2009