I had the same problem with the DMX window going crazy when not in use. I think the secret is to disable when your not using it. I know its no big deal, but it annoyed me and I ended up going with xlights instead (not just for this reason).
Apparently if you have BOTH LOR and DMX mapped in your sequence, you cannot just test the DMX channels/hardware ... without an LOR adaptor also connected.
Right click on the Light-O-Rama icon in the toolbar to select the Launch at startup option ... that starts the LOR Control Panel at startup.
The LOR Comm Listener only comes on if all of the following are true:
(1) You have the LOR Control Panel running.
(2) You have at least one DMX adapter set in the Sequence Editor's Network Preferences dialog.
(3) You have the DMX Listener Port set to something other than 0 in the Sequence Editor's Network Preferences dialog.
So, if you don't want the LOR Comm Listener to run, then change one of those three things. However, be aware that you won't be able to use native DMX devices while the LOR Comm Listener is not running.