Tvheadend

How are you starting tvh? Or what does ps -eaf | grep tvh say about the process?

EDIT

The tcp: bind: *: Address already in use bit suggests that tvh is already running, perhaps...

It seems TVH is already running, but perhaps not stable since the PID is permanently changing.

ps -eaf | grep tvh:
UID PID PPID C STIME TTY TIME CMD
hts 11982 1 0 11:25 ? 00:00:00 tvheadend -f -u hts -g video
qa 12003 31168 0 11:25 pts/1 00:00:00 grep --color=auto tvh

after a few seconds:
UID PID PPID C STIME TTY TIME CMD
hts 12005 1 43 11:25 ? 00:00:00 tvheadend -f -u hts -g video
qa 12026 31168 0 11:25 pts/1 00:00:00 grep --color=auto tvh

Sounds like you've got an installed version that, as you say, is crashing and respawning. Check syslog, you'll see the crash and startup messages there. Xubuntu Trusty is a perfectly good base, so I doubt that's relevant.

Check your tvh version, see if you can work out why/where it's crashing, try a later version; after that, you're into gdb and backtracing to see why/where it's dying. You also need to figure out why you have two versions - I presume you have one installed as a service (from PPA or dpkg -i *.deb) and one that's starting independently (e.g. from build.linux?). If it's not that then you perhaps have 3.4 and 3.9 installed at the same time (somehow...!). ps -eaf | grep tvh would be a starting point.

FWIW, I had a lot of crashing with the newer versions when I jumped from build 1987ish to 2100+ - it eventually seemed to fix itself when I 'walked' through 1990, 1995 and so on. I presume I had a config issue that incremental upgrades dealt with better than the big leap, but that remains a guess.

After I installed and uninstalled TVH a few times, it suddenly works since today morning.
I have no idea why it's working now??