No video after using visualization on WMP11 and WindowsXP SP2

My Windows Media Player 11 was working fine, showing the video and audio of a .mpg file. I selected a visualization by mistake and the video output of the mpg went away. I then selected the "No visualization" option and as a result I can no longer play the video portion of an mpg in WMP, just the audio and a black screen. Anybody know how to fix this? I'm running this on Windows XP Pro w/ SP2. Thanks