Unable to type

I’m not sure what I did, but I was working on a project when a large screen came up blocking my entire desktop. I managed to get that away by using Escape, but now Scrivener is extremely slow. At first, I couldn’t type at all. I’ve tried closing and reopening it. It seems to be getting better but we’re talking ten or more seconds between typing and it appearing.

I have a hard deadline July 1st so this is happening at the very worst time possible. Any idea what’s going on or how to fix it?

What did the large screen say, if anything?
Apart from that, shutting down the computer and restarting it might be the most immediate strategy.