We're seeing an intermittent issue in our process where a user will submit an InfoPath task form and sometimes InfoPath will close and show the "Form has been closed" screen and sometimes it will show an error with the following details: 

It appears to me that InfoPath is attempting to re-open the task form even though the process has already deleted the task form from the document library when the activity completes. It's a big annoyance but; however, it doesn't disrupt the process since the activity has already completed by this point.

Has anyone else seen this?  It doesn't happen all the time and it doesn't happen for all activities which makes it even more frustrating.

Thanks in advance.