""Windows Media Player cannot play the file. The Player might not support the file type or might not support the codec that was used to compress the file"

I have tested Windows Media Player with .mp3 and .wav files - no problem."

"What does K-lite codec do?"
Quote:
The K-Lite Codec Pack is a collection of audio and video codecs for Microsoft Windows DirectShow that enables an operating system and its software to play various audio and video formats generally not supported by the operating system itself.