If you're having problems with specific files, I'm wondering if it may be something about the filenames. The MacOS and Windows have different characters that aren't allowed in filenames. Windows won't accept a filename with any of the following: /:*?"<>| I'm not sure what the result would be if you tried to copy such a file.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken