From your comment I see two separate issues:
1) dictionary has data those are not correctly UTF-8 encoded (you don't now what to do with them)
2) Gnome dictionary is confused with data those are not UTF-8 encoded and stops to work correctly. Restart needed.
From your comment I see two separate issues:
1) dictionary has data those are not correctly UTF-8 encoded (you don't now what to do with them)
2) Gnome dictionary is confused with data those are not UTF-8 encoded and stops to work correctly. Restart needed.