Hotpoint CTD80 Time to End jumps an hour after only 10 minutes running?

I have a Hotpoint CTD80 tumble dryer, and when I start the cycle (any cycle) it runs for 10 minutes and then jumps the program, displays Time to End of around 20 minutes and then finishes after 20 minutes leaving the clothes still wet... Any ideas? Is there a faulty sensor associated with the Time to End Function that may be faulty?