Zanussi Jetsystem + 16581W won't open the door after a wash cycle?

Hi all, can anyone help me to understand why our Zanussi Jetsystem + 16581W won't open the door after a normal wash cycle. The display shows 00:01 minute to go but it doesn't move on from there. The lock light is flashing as if it is preparing to open the door.

Have tried 2 different wash cycles and get the same result, so it's not just 1 particular washing program causing the problem.

By moving to an additional spin cycle the door does unlock normally so it doesn't happen on every program either.