White line appearing in an all mesh level?

The question says it all, how can I stop this line from appearing in an all mesh level. The line doesn't show up in screen shots, so its hard to show you what I'm looking at, but if you look at any simple all mesh scene, you should get the same results. Any help would be appreciated.

Justin, here are the screen shots. I was able to get the white line in one of them:

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