Movie Poster Corrupting File

When I occasionally rip DVDs to iTunes, I like to upload the correct movie poster and put tags on it and everything, and normally there isn't a problem. However, with one, namely Robin Hood (2010), whenever I upload the picture the movie file becomes corrupt and turns blank and forces iTunes to restart.
I've tried this many times because at first I though it was just some picture I downloaded that had a virus in it, but everything, regardless, has corrupted it. And it's only that one movie. Has anyone had a similar experience?

Well I think it should work if I just upload the poster with MetaX, so never mind. Still really weird though, and I think that happens if I change anything regarding it. Maybe there's some protection on the DVD, but I wouldn't know what.