Nasty bug, have had it happen twice now and not sure of what I have done to make it happen.
All the text in the message bar disapires, can't see what anyone types, not even my self. I don't see the text when I type it either, only the red text marker moving forward. FPS drops after this happens, usually from 60-75+ down to 10-15. I don't have any FPS problems what so ever otherwise, even with many players nearby.
Also, on the clipboard, after I push setup or E6b or anything else, the text under those choices are also gone.
Second and last time it happaned, last night, I pushed Tab (to expand message window) at the same time as I pushed and relased the 1 numpad key (to check 7 oc), trying to reproduce it but no luck so far.