Probably a leaking hose. The movement of the drum will vary a bit from wash to wash depending on the load you have put in and distort the hose differently.
Pull the plug out of the mains supply and remove the back of the machine. You might be able to see where the water has been coming from.
Failing that you may have to "get a man in" - not cheap but quickly fixed.
Your drain could be blocked - causing the water to be backed up. Happened to us, flooded kitchen twice. The outside drain didn't look blocked until we checked it as the water was being pumped to it, when it filled and blocked the pipe. Then it drained in a matter of minutes, so we had to look at it at the right time. Cleaning it out solved our problem.