InfoPath 2007 has eliminated access to TaskPanes[3] and TaskPanes[4]. These were available in InfoPath 2003. If any of your code tries to access these panes you will encounter wierd problems as we have found that no explicit error shows up. It fails silently and then parts of code just run not as expected.
Shiraz Cupala / Microsoft InfoPath MVPQdabra® Software / Streamline data gathering to turn process into knowledge