Problem changing channels

I'm having trouble changing channels - either it works great, or one of the following two scenarios happens

1) The channel changes, but the information overlay at the bottom of the screen stays on for up to 2 minutes, meaning I can't do anything (ie: continue changing channels)

2) The channel changes audio stream, but picture shows "loading channel X" for up to a few minutes... and then, ocassionaly, problem 1 happens when the video finally shows

Anyone else?