Comment 4 for bug 104932

"The computer was low on hard-disk space so Mythtv chose to expire a previous recording. But the recording it chose was the recording prior to the programme it was recording just at this moment. Shouldn't it take something older?"

Check out the options you have for expiring of files. You'll prob wanna use the option to delete older files based on there recording profiles, rather than the default of the latest recordings.

Also what file system are you using for the string of the recordings, I've had my backend crash before whilst using ext3 with slow delete since it couldn't free up the space required for the new recording quick enough.