My guess would be: you are running out of memory. The process which Limetech uses to run the GUI can be bumped out memory and then can NOT be restarted. One thing that some people have found which helps is the set the process priority for that process higher so that it does not get bumped.
IF you want to remove Dynamix, read this post:
http://bergware.github.io/dynamix/
I believe removing the file /boot/plugins/dynamix.webGui-2.2.10-noarch-bergware.plg and rebooting should remove Dynamix. You will then be using the default GUI and, if my assumption is correct, you will soon have the same problem with it. (You could also just rename it to with a '.old' extension...)
Hi Frank
Removing the plugin file did indeed remove the Dynamix GUI. Thanks! The memory problem you are talking about... is that connected to the amount of available RAM? I have 4GB but am running, Couchpatato, NZBDrone, SABnzbd, Transmission and Plex Mediaserver. A bit too much I guess?