FYI I was able to (somewhat) resolve this issue. I was suspicious that my channel setup may have had something to do with this and I was right. For experimentation purposes, I restored my channel defaults and went back to the Movie Guide and no crashing.
I have an Avermedia tuner card and am using the Avermedia ClearQAM utility to locate QAM channels and import them into Vista Media Center as digital channels. By labeling the channels prior to import in the ClearQAM utility with the proper channel identification, I am able to avoid the issue of the channel mappings being overwritten when the channel guide is updated at night. Well, something about how I named some of the channels must have caused the movie guide to crash. I'll probably start by only importing a minimal set of channels and see what happens.
