Hoover Six 1100 Door Won't Open, At First..

If the door interlock has a rubber pressure tube connected to it then it could be a blockage in the pressure system preventing the air from escaping. Not all washing machines have them, but here's how the system works -

The door interlock has an internal locking peg operated by air pressure

When water goes into the tub some of it goes into a plastic compartment called a pressure chamber

This pressure chamber has a small rubber hose connected to it which goes to a pressure switch to control water levels and sometimes to the door interlock too

Water entering the machine forces air up this small tube and locks the door interlock

When the water has pumped away water drains from the pressure chamber and releases the locking peg on the door interlock

Sometimes a partial blockage in the pressure chamber (at the tub end) prevents or slows down the release of air pressure when the washer has finished pumping out the water so the door still won't open for an hour or more after.

If your door interlock has a rubber tube attached to it follow this line of inquiry. If it has only wires connected to it then it can't be this, though it's possible the door interlock is sticking.

See this article for general help with a door which won't open.