Ahh but the problem is from *TiVo* - not from a pronto. (Or as far as I can gather from the message that's the problem.) The Sky box seems to be getting repeated codes from TiVo when TiVo wants it to change channels.

First place I'd start is try a different speed setting for the IR codes that TiVo is using - I had a similar problem with my old Pace OnDigital receiver when I moved my AV kit from a position where it was in direct sunlight to a shaded position. I had to change from "slow" codes to "medium" codes otherwise I had duplicated commands being received. It may be a similar problem that you're having.

Phil