I have a combined fe/be and another separate front end. With the remote f/e switched of and just using the combined machine, when selecting a theme other than mythbuntu, the connection to the backend drops out randomly. If I leave the theme as mythbuntu or this behaviour does not exhibit.
I have found that this issue was related to an earlier problem here:viewtopic.php?f=36&t=3952#p19329
After a reboot the deletion of cards and video sources and redoing card and sources setup and a new scan sorted out my problem. It does seem peculiar that an EIT issue can cause a backend dropout.
I thought I'd post this so others that experience this can benefit.