Why does progress values change in a Plan when expanding all tasks?

 We are running RTC 6.0.3 and I have a user who complained of confusing data in her Release Backlog plan using the basic Iterations view.  The plan is against a parent iteration with 5 sub-iterations. When opening the plan the progress of the parent iteration shows a progress of 67/311 pts.  If she then does an Expand All to expand all the epics to their stories and tasks the progress changes to 36/209 pts.  We have tried adding up the progress points on the sub-iterations and can't come up with any combination that explains the overall change.  Can someone point me to anything that can explain this?  She is just trying to get a handle on the overall points in her sprints.