I'm not sure if this is unique to NWE or to Tiger 10.4.1. However, it happens to NWE very often.
When I have other application running, and try to quit NWE, it won't quit. And when I open the force quit window, the NWE entry will turn red with a message of No Response. I have to use force quit to get out of the NWE, otherwise, the spinning ball will keep going forever.
It's a very annoying problem.