coverage.log, but no coverage.xml

I'm trying to profile an extension written for a 3rd-party C++ application. I can use NCover to start the application, it connects fine and everything works, but when I close the application, the NCover process doesn't close. The only thing I can do is kill the process, but then I don't get an xml file, just a dump of the instrumentation and exceptions (52MB worth). Any ideas?