Why Does Music Stop Playing in Windows Media Player?by Scott T. Harrell
Windows Media Player is an intuitive, easy to use music player. Occasionally, however, you might have your favorite song cut off mid-stream. The reason is usually something fairly basic.
Play Has Been Accidentally Paused Or Stopped
Computers often have keyboard shortcuts programmed to control applications like Windows Media Player. Check the screen to make sure the arrow-shaped "Play" icon is showing; if not, you may have paused or stopped the music by hitting a certain key or keys.
File Is Incomplete Or Corrupt
Some audio files may become incomplete or corrupt through conversion from other formats, downloading or viruses. Open another file in Windows Media Player; if it plays without problems, the song that wouldn't play is probably corrupt.
Buffering refers to the transition of data from one area, such as a website or computer hard drive, to another, such as the Windows Media Player application. A slow Internet connection, overworked computer processor or lack of available memory may cause large audio or video files to stutter or pause as their data "catches up" with the player.
From time to time, any computer application can freeze up or stop working, for a variety of reasons from compatibility issues to buildup of errant bits of data. Windows Media Player is no exception; quitting and re-starting the program should help.
Operating System Crash
Like applications, computer operating systems as a whole can become bogged down in tasks and freeze. Re-starting the computer will usually fix the problem on a short-term basis, but defragmenting its hard drive and installing maintenance software are recommended.
- link Microsoft Help