Are you using the same exact converter you always use?
If you copy some to the media to your local drive, make new project, will it run?
What is different about these files you converted than the other ones you say always work?
I did look more closely at the files - some of them are ridiculously large (like 50GB after converting). Perhaps the drive is having issues because they're so big? I'm copying them to a different drive to see if it makes a difference (and also because I'm running out of room - I have about 30 of these files to convert, and I need them all in the same place).