Not sure exactly what you mean. I can't seem to reproduce based on what you said. Is it giving an error message?
If it says something about an invalid application please check for an event in the event viewer under Applications and Services -> Media Center ... (the event will be marked as "Information" even though I would think it would be an error)
I to have the same problem when I use my Xbox 360 as my extender - I navigate to the Record TV HD strip and choose the movie section. I then go into a recorded movie.....I review the movie information or start the movie. When I hit the back button, I then go back to the movie information section. At the point when I go back one more step (while leaving the movie information section), the process takes about 5 - 10 seconds to get me back to the menu of my movies listed.
Hope that makes sense.
Plus, on the PC, when I add something as a favorite, I did get an error, that the Record TV HD is not responding and the disable box or OK box pops up in WMC.