I opened Windows Media Player to play back a video, but I found many of the controls-and even some clips-disabled.
Ah, this seems like a cache problem. Windows Media Player (WMP for short) stores basic information about each clip you play (such as the clip length). WMP uses this cached information to optimize playback performance the next time you play the clip. It’s a slick system when it works, but when you change or replace a clip (perhaps with an updated version), WMP continues to use the old cache information. This can mess up the player controls, or disable the clip entirely.
To work around this problem, give each file iteration its own unique name, or move the edited/altered file to a different folder. However, you may also need to periodically dump the WMP cache file. Select Start → Search → All files and folders. Under “All or part of the file name,” type wmplibrary*.db. Under “Look in,” select Local Hard Drives (C:), and then click the Search button. When Search locates the files, right-click each file and select Delete.
For best results, run a DVD movie in windowed mode while you adjust the color and gamma settings. This keeps the controls from obscuring the movie image.
Windows Media Player tells me to decrease video acceleration when I try to play a streaming video.
With Windows Media Player running, select Tools → Options, and then click ...