thread problems with Java JNI

A simple test program using boost::thread works fine, but when I try to use boost::thread in a DLL library which is called from a Java thread, the thread blocks forever in the constructor for boost::thread. Looking at the source code for boost::thread, I see that it blocks on a condition waiting for the thread to start. Maybe the thread never starts? So. I modified my code to use _beginthreadex() directly to start my worker thread. I hoped to at least get a better idea of what was going wrong, but the code worked flawlessly. Are there known problems with using boost::thread from a DLL? Any other ideas? Thanks, Justin Michel