I've been having two problems these last few weeks.
The first one is when I try to save a replay. Sometimes, I can't type anything in the description area, so I can't save the replay. On some rare occasion I can. I have no idea why.
The other maybe related problem is when I want to decline a game - On some occasion, I can't type anything in the reason why I can't play, so I have to click on the "no thanks" button. That's not the end of the world, but I find that a little rude.
Just for information, I've never had any problem typing in the chatbox in a game, so this is limited in the two cases above.