Thompson HD box fan problem?

[StephenCai]

Apologies if this is the wrong Forum....
All has worked well with my Sky HD Box (Thompson). I was always slightly curious about the fan which stayed on for 20 seconds or so after turning Sky off and the television.
Tonight, however, the fan was louder than normal, and remained on until I eventually decided to turn off everything at the mains (that stopped it!) Anyone know if there is a problem? It sounded like a videotape rewinding, and was about 3x louder than normal! Looked at manual with no success.

Any ideas?

[contraste]

It does seem to be a problem with many of the Sky HD boxes, mine included.
If you search the Sky HD forum you will find lots of similar complaints but sadly no fixes AFAIK.