I too have 2 Sat-B50's and 1 SAT-A50. I only have this problem on the top of hour. Off-hour and guide works well. Have not verified this it on the 30-minute mark nor when Dolby Digital movies are being transmitted. This seems plausible though, taking into consideration the bandwidth requirements.

I switched from the Dish Network to DirecTV and this slowness of the guide took some time getting use to. The Dish Network does not exhibit this issue. I know the Dish Network has a higher bandwidth capability though.

Brian