This sounds very similar to a problem I've just fixed on our dryer today. The original fault on ours was that the heater had stopped working. After checking the thermostat and finding it had opened I reset it and replaced the back onto the machine. I switched it on and low and behold it tripped the breaker on the fuse box. I took the back off again and checked the heating element and thermostats to see if I had accidentally done something when reconnecting the thermostat. This is when I noticed that one part of the heating element had slipped from the mounting and was touching the dryer casing. I reset this, replaced the back and switched the machine back on. Washing tumbling as we speak. Did you or anyone else do any work on the machine before this started to happen? If so, then recheck that everything is where it should be. If not, then you have a short to earth somewhere that needs to be fixed. Possibly your heating element has burned out and is going to earth. Depending on your personal capabilities you might be able to remedy this. Just make sure the appliance is always unplugged from the mains before you start looking / working on it. I hope this helps.
Gray
January 2010
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix tumble dryers.