[flexcoders] Module Error after loading module 2nd time

[boy_trike]

My main app, just loads 1 of 4 modules.  There is a combo box with a list of 
the modules.  If 
I re-load the current module then run a function that dispatches an event I get:

TypeError: Error #1007: Instantiation attempted on a non-constructor.
        at mx.controls::DataGrid/mx.controls:DataGrid::drawSeparators()
        at mx.controls::DataGrid/mx.controls:DataGrid::updateDisplayList()
        at mx.core::UIComponent/validateDisplayList()
        at mx.managers::LayoutManager/private::validateDisplayList()
        at mx.managers::LayoutManager/private::doPhasedInstantiation()
        at Function/http://adobe.com/AS3/2006/builtin::apply()
        at mx.core::UIComponent/private::callLaterDispatcher2()
        at mx.core::UIComponent/private::callLaterDispatcher()
        at [enterFrameEvent]


Is this a known bug with modules?

thanks
Bruce