That you can write to the drive suggests that it is working well enough, but since you can't read existing files, I'm going to go out on a limb and suggest that it is a permissions issue.

If you get the info for either the NTFS drive, or for individual files & folders on it, can you verify that you have read/write access? Obviously, you've got it for files that you want to create, but I'm thinking that the MAc doesn't think you own the files you are trying to copy.

Good luck,
Perry