Hi
Glad you like the mod.
Without having an extra look at the code, I have no idea why this would happen. Don't think it is related to the modded dll, but I cant guarantee it to 100%.
Any particular file type, like .img or iso when this happens? Can you play the file from the IMDB page?
One way to find out is to switch back to the original dll and see if the the error persists. Hope you get any wiser from this...