Sql Developer v4.1.0.18 Build MAIN-18.37
The export data dialog (right-clicking in a query result) suddenly stopped working this morning. The dialog window where I normally get to choose a file format and destination refuses to say anything other than "Internal Error when attempting to create this panel", followed by a big chunk of java-related stuff:

Everything was fine yesterday. Can someone help me get this fixed, or point me in the right direction?
If I launch an older version (v4.0.0.13 Build MAIN-13.80) the export dialog works as expected...