Most likely the thermal cut out unit. Had the same problem with mine. See this forum for advice and part;
http://www.ukwhitegoods.com/modules.php?name=Forums&file=viewtopic&t=8990&start=0&sid=0580df2e3dcb5ab7a82f150d46d6ea6d
Although if in doubt, call an engineer!
Bert, August 2008