sky + box freezes?

my sky +box when playing a recorded prog. will freeze for 30seconds then switch itsef off onto standby.Five minutes later green light comes on then "use your sky box" clip and eventualy the all channels screen.I then need to go into planner select the prog I was viewing fast forward to freeze point and start to watch.This can happen 2/3 times a night then be ok for 2/2 days. Any advice!!?

bigears
January 2010