I am currently attempting to deal with an issue with releasing a FlowDocument resources. I am loading an rtf file and putting it into a FlowDocument with TextRange.Load. I n
Make sure that the Parent of the FlowDocument isn't hanging around, see here. "Instantiating a FlowDocument automatically spawns a parent FlowDocumentPageViewer that hosts the content." If that control is hanging around it could be the source of your problem.