That error message should be fixed now if you download the newest version, also some performance improvements but that will be ongoing. I'll look into certain keys not rebinding properly. In the meantime you can click the button in the bottom right to open it, but I'll get the hotkey fixed as well.
Indeed the error message is fixed now.
About key binding, it's something else.
I've set PUIE to move, P being "forward". But ingame, each time i go forward, the equipment window opens/closes, as it seems P is hard binded to that. So, P has two distinct function, one i set manually (move forward), one i cannot remove (equipment window).
I didn't try every keys, but i suspect it's not the only one, so if you can look at that, i would be great.