Every time I log in, I get the following error:

Error: AceHook-2.1: Attempt to hook a non-existant function "CastSpellByName"
File: ...ns\LunaUnitFrames\libs\HealComm-1.0\HealComm-1.0.lua
Line: 420
Count: 1

If it helps in diagnosis, etc, more than half the time, that error will stop Bartender2 from loading, so I have to keep logging out and logging back in to get Bartender2 to load, (note: the Bartender issue was also there when I tried using NotGrid, which is why I'm trying Luna).

Note also: I'm not using Healcomm. I downloaded it once, at the suggestion of Shagu for pfUI, but long ago deleted it, (and pfUI) from my addons folder.

This is either another addon thats causing it or you have corrupted settings.