Originally Posted by videohog
Please read this tutorial : Windows Media Player (WMP)
In Windows Vista x64, the 32-bit edition of Windows Media Player 11 (WMP 11) is set as the default Windows Media Player. This is done to avoid and reduce any compatibility issues or problems that may arise with codecs or other DirectShow related plug-ins or add-ons that a majority of are still built for 32-bit operating system. However, if you decide to use the 64-bit version of WMP11 with your 64bit Vista, you can use a few easy methods to launch 64 bit WMP11 or simply switch, change or swap the system default media player to x64 Windows Media Player, and revert back to x86 version when you need to.