Whenever you get anything like that happen just wait thirty seconds or so before switching your Amiga back on. Sometimes stuff from games gets held in memory and evades the soft and hard boot.
I find the same thing on mine. It seems like unplugging it helps but all I really think that's doing is adding to the time that the power is turned off.. nothing magical about pulling out the cord, but it works. I guess its all those lovely capacitors.
