When using quicktime in Windows or OS X, this error is occasionally seen when trying to view video files. Here is the cause and the fix.
The movie could not be opened.
An invalid public movie atom was found in the movie.
When ripping and viewing videos, this is an error message that is difficult to interpret.
Basically this error occurs when a program converts a video for which the correct codec is not installed.
For example, many programs will convert from divx/xvid to Apple friendly formats for iPods or AppleTv. Most of these programs assume that the correct video interpretation software (codec) is installed. If it is not, the program will convert it anyway. The ultimate unusable output will spit this error.
The fix is to install the correct codec on the machine before performing the conversions.