Not really a solution... (take it as a last solution...)

(first make a backup of your actual "incomplete" folder ) exit LW (with right click on the small icon near the watch -> Exit ) -> go to your actual "incomplete" folder -> delete everything -> go to the "incomplete" folder on the external hard drive -> select all files -> copy them -> go back to your actual "incomplete" folder -> paste them here -> start LW...

Good Luck !!!