Hotpoint wmt05 door problem?

Hi Ive got a Hotpoint WMT05, that on loading washing and turning on the machine starts and after approx 5 mins stops and the door locked light flashes. You can then open the door mid program.

Is this a door switch fault or somthing else. If I switch it off and leave it a while I can re start the program only for it to do it again.

Any help would be greatly appreciated.

Thanks