I had the fault H2O. My machine just kept filling with water and would not stop, flooding my kitchen.I nearly called out a Hotpoint engineer which would have cost nearly £90 ! Instead I decided to have a look myself. I removed the top by undoing the two screws at the back of the machine and sliding the top towards the rear of the machine. Standing at the back of the machine, on the right just below the top, I saw that a pipe had come off what looks like a pressure switch. I replaced the pipe and this has fixed the fault. I had to switch the power off at the socket to remove the fault from the display, but you should do that before removing the top anyway.
I really hope that this helps and stops you having to fork out for an engineer.
Iain, April 2007