I don't think this has been posted here before - at least I couldn't find anything related.
The comment here reports a problem which I have encountered as well: As long as the sitemap plugin is enabled I get a blank page whenever I save a post. The dashboard is blank as well, except for the menu bar and the two boxes saying "Dashboard" and "Latest Activity" (but no content).
I also seem to have problems to send and receive trackbacks and pingbacks as long as the plugin is enabled. When I disable it, everything works fine again.
How could these things be possibly related?