Hi Jerry,
1. The user can click the button in the second screen shot and the task will be completed but the user is never returned to the site. You'll notice that the second screen shot is a full screen view of the task form which (prior to clicking the link for the InfoPath form) was a modal popup.
2. Yes, I don't believe this is a permissions problem.
3. Oddly and maddeningly the InfoPath form now submits successfully, but the issue with the task form remains.