The Windows Media Load Simulator (occasionally abbreviated as 'loadsim') tool was created to help stress test Windows Media Services (WMS) servers. Since WMS does live streaming and uses application specific control messages over RTSP and HTTP using a web server stress tool doesn't really work. Also, since Windows Media Player actually uses a good bit of CPU to render the audio or video a tool like loadsim is necessary. It worked well back in the early 2000's, but since the default protocols have changed from MMS to RTSP and the MMS protocol has been completely removed from Windows Media Player 11 and later running loadsim has become a bit dicey on modern systems. I've had a number of people ask me about how to get it to work, so here are some of the troubleshooting steps that I've used with probably 80% success.