Amstrad Sky+HD box?

I've got an Amstrad DRX780UK Sky+ HD box and three times tonight I've had to do the power off reset as the majority of the channels reported "no signal" I use my own dish for one signal and a communial dish on the flats for the other. The signal level and quality is shown as good after the reset.
Is there problem with these boxes overheating ? and is there a known fix for this type of fault ?
I'm planning on a short holiday soon and I don't want to come back to a load of recordings of blank screens !!