If you're having issues with map arrow or inventory slots...
I was having lots of issues with the GUI. The map arrows were all over the screen (made it 'fun' to survey). I couldn't put stuff in the right spot in my inventory, couldn't put things in chests/banks, the 'drop item' box was in the middle of my inventory icons. Basically no fun at all!
But I think it's because I changed some settings and even when I tried to put them back to default I had issues. Was ready to give up but tried one last thing... logged out and renamed the new GorgonConfig.txt file so I would have everything back to default.
The downside is I don't have all the changes and preferences I liked - I'm back to vanilla. But it's playable again. So if you're in the same boat, you could try the same thing. After all, you can always delete the newly created config file and rename yours back!!!