My experience of PC behaviour has shown me that the cooling of board components can be very useful at preventing intermittent failures.
There is mention in the forum archive of people adding a heatsink (and fan) to the MPEG chip in the Tivo with the hope of fixing the white flashes of Mode 0. However, there doesn't appear to be any conclusions posted.
Anyone tried it and can say whether there is an effect ?
I reckon it has to be worth a try.