Thanks Bryan. I am sorry for wasting everyone's time, but I will post my solution here in hopes of helping someone else. After checking the differences, I googled for the error messages in my log, and found the slimdevices forum messages you mentioned in April. That lead me to the source of the problem - my router (a D-Link Gamers Lounge DGL-4300). It had application level gateway configurations for MMS and RTSP that were supposed to help applications that used these protocols. However, they were actually blocking mplayer from using these protocols with many servers. I turned off these settings and everything is working fine.