For whatever reason, opening chat and hiding the HUD sometimes messes things up. Afterwards, all I have is the mouse that shows up when opening chat, and the HUD can no longer be shown again. I pressed pretty much every key on my keyboard, and nothing does anything. Once in the past, I had this where it showed the chat, and I was able to fix it somehow. Another time, it fixed when I respawned. But this latest time, it was unfixable.