This happens very rarely now, but it’s happened at very critical moments on both occasions. While in combat my keybinds will suddenly stop working and if I try to mouse click an ability, it will link the ability I click into the chatbox.
For instance, my F1 key is bound to my mouse wheel button (Mouse 3). While in combat, I will be doing fine when suddenly all of my abilities will stop working via keyboard/mouse button press and when I try to click them via left click with the mouse, it automatically links the ability into my chat window. If I was whispering someone prior to this, it will send the ability to them immediately.
The only solution I have found to fix this is to terminate the client and restart it. But this makes participating in things like spvp very frustrating.