Most problems are a function of simply missing one of the steps of a installation or update.
Many times an Internet viewer simply does not realize that they missed something. Another source of frequent trouble is that a viewer changes something else on their computer, say they install a new software or hardware, and it interferes with another aspect of their computer. Please keep tract of the recent events that have occurred within your computer when trying to diagnose a current problem. When I attempt to play a movie I get only white frames for my video even when I can hear the sound track. If your computer does not have the same codec to decompress the video, QuickTime plays back the parts of the movie it knows about.