Object Explorer Filter gives null reference error. (4232017)

Receive the following error when trying to use filter in Object Explorer for any object.

"System.NullReferenceException Object reference not set to an instance of an object.

Stack Trace: at Quest.Toad.DatabaseBrowser.ObjectPaletteControl.FilterContext_ContextChanging(Object sender, TrlContextChangedArgs args)
at Quest.Toad.Settings.TrlContextCollection.TrlContextChangedHandler.Invoke(Object sender, TrlContextChangedArgs args)
at Quest.Toad.Settings.TrlContextCollection.OnContextChanging(Object sender, TrlContextChangedArgs args)
..."

Once the error comes up, it continues to come up.

Disable the Database Explorer window and restart Toad.

Verify Tools | Options | Database | General  -- disable setting for "database explorer" under "Open on New Connection".