I've been having similar problems but haven't had enough time to properly look into it yet.

When I try and enter a search string key presses are occasionally ignored or misinterpreted as another character. Sometimes it even changes some of the already entered text to something else.

In addition I've had it refuse to shut down using the link in the top right a couple of times. Shutting the browser window does the trick though.

I'm also using the English dump, but I'm not convinced that the dump used should be causing these issues. Hopefully I'll have some time to properly play with it over the weekend.

Hope we can get it sorted as it is an amazing little app when it works.