Mine did this a few times over the years, same model too. It's a build up of water underneath the wash tank (about 3 to 4 litres)
It's not too difficult to sort.
Ensure the dishwasher is empty, pull it out from the wall, get two or three large old towels under the machine and gently tip it onto it's side soaking up the water in the process.
Put back upright again, job done till the next time in about 12 months or so!!
I heard on here before it's a design fault with Hotpoint Aquarius machines.
Jon B, February 2011
