It sounds like your character was being seen as "stuck in combat"... that disables certain functions. For instance, the "R" key fires your ultimate, but if you're dead you can't fire your ultimate, and in combat you're being restricted from chat...

The state engine is to some extent screwy in the game. I've seen similar problems occur. As you discovered, doing a temporary change on control inputs can solve some problems.

Suggestion: switch your controls for "R" and "T" such that "T" fires your ultimate and is used for secondary choices on dialogs. Among other things, it'll prevent you from accidently firing your ultimate when you don't want to. I've done that on all eight of my characters. Now, if I accidently hit "R" during combat, it just changes the quest that my quest lof points to... no big deal.

Now if I could just find an appropriate key to switch for "Q" I'd quit burning potions when I'm not planning to...