Please turn on logging, and capture a log file for such behavior.
Make sure you restart MC or reset logging right before you start recording, so that the log file will not be too large. Email me the log.
yaobing at jriver
If the issue started in MC29, it is likely an issue of your hardware.
Also, if you use MC30, because of the new time-shifting method used, your recordings will be in TS even if you configure it to JTV. I have just made this new time-shifting optional, but the option will be available in the next new build.