> between the the download of the pdf and the crash were roundabout 50 minutes

Ok, now the picture is a bit more clear for me. So it looks like JVM releases resources, allocated by native DLLs, before the Java class is actually garbage collected. It is strange that the garbage collecting makes that long pause – on the other hand the Java spec does not limit the time.

Next week we plan to release an updated version – we’ll add a workaround for the issue.