Getting strange characters in third party apps. How do I fix it? I don't really know how to explain this problem, so i'll just show some screenshots. GIMP is completely unusable. it looks like it's in another language. Visual Studio does it too, but only in certain cases. even safari has become a problem. That leads me to believe that it's an OS issue. Strange characters appear randomly where normal english text should be. Can anybody help?
Font Book > file > restore standard fonts > restart

Is the first thing to try