I've been having an issue with some of my media discs lately, I have several discs with small video files on them (between 1 and 4 hundred MB), and after burning the files to disc, I test each and every disc to make sure all the files transfered successfully. However, months later I'll go back to pull up a video, and find that one or two files on about 40% of the burned discs are no longer readable and cannot be opened or copied. The discs differ in brands, and the video files are various types (though most are .avi or .mkv). I replaced my disc drive several months ago, and upon discovering the problem, I tested discs I had burned after the switch, and found the same problems. I keep all the discs on a shelf in thin-pak jewel cases, but can't find any other constant between the problematic discs. Any ideas?