Every now and then when trying to export an MP4 movie, the rendered file is corrupt and file size is 0 KB. Sometimes when this problem occurs, but not always, I also get a warning message saying "File importer detected an inconsistency in the file structure of... Reading and writing this file's metadata (XMP) has been disabled". At first, I thought this was the reason for the problem, but since the warning message doesn't occur every time, I don't think it is. Also, If I try exporting the movie once again without making any changes, it seems to work fine. I have a fairly recent computer with Windows 7, a good amount of hard disk space and RAM memory and a Radeon HD graphics card also with a good amount of memory, so the hardware shouldn't be causing the problem, I think. Suggestions, anyone?