I have an sControl in a popup window that contains a link to edit a Task.  The link is formatted like this...

/TASK_RECORD_ID/e?retURL=/servlet/servlet.Integration?lid=SCONTROL_ID

The link works fine, and I'm able to edit the Task record.  When I save the Task, I am redirected back to the sControl, but I am getting an INVALID_SESSION_ID fault.

Any ideas?