I was trying to add an image from hyperlink, expecting to create HTML tag. I clicked on the Insert > Image (File chooser or Link) and filled in the complete url for in the filename field in the form that pops up. After doing this Freemind keeps occupying CPU in running mode and all controls are lost. It sort of hangs up.
In my opinion such behavior is a bug as it should gracefully error out / time-out instead of hanging up.