photoshop path pen tool error? bug?

Update to the most current version.

Reset the tool preferences, and try again.  Here's a link to show how that's done.  If that does not solve the problem, go to settings General and Reset Photoshops preferences on quit.  That resets all the prefs across the application that you may have used so, doing this may have you going back through PS to adjust your settings back to the way you prefer them, but doing so will put things right.  Baring that keep your PS version current is a very good plan