Tvheadend

My guess is an argument between the user under which the tvheadend process is running (you if you're using -C, or as specified if you've got -u, or hts as default - ps -eaf | grep tvheadend will tell you) and some elements of your system. The 401 suggests "not authorised" - beyond that, I can't say.

I'd guess at:

Permissions to read/write the configuration files
Permissions to access the webui files
Permissions to access the tuner

... and similar. You may have other error messages around this that give you more information - warnings, for example.

xbmc@PlexTwo:~$ ps -eaf | grep tvheadend

hts 978 1 2 18:04 ? 00:00:06 tvheadend -f -u hts -g video
xbmc 3378 3282 0 18:08 pts/0 00:00:00 grep --color=auto tvheadend

Nothing as far as other error messages.

is it just r/w rights for the directories?

Looking at my system, most of the config directories are hts:video (700) with some hts:hts (775); files are then various permissions, but they obviously have to be readable to hts as the tvheadend process.

Webui files (/usr/share/tvheadend/src/webui/static) are root:root, 755 on directories and 644 on files.

Tuners, the /dev/dvb/adapterX directories are root:root, 755 and the contents of them (demux0, dvr0, etc.) are root:video, 660.