Disappearing Sprites

I have been experimenting with map navigation by changing the camera position and extent based on the mouse state. My scene only containes 100 static sprites in a 10 x 10 array and a few of Gui elements. The following image shows the screen with most of the tiles visible. Some of the bottoms ones were cut off because the sceneview doesn't fill the screen.

http://i286.photobucket.com/albums/ll95/lacota_rds/NoMissingTiles.jpg

When I move the camera some of the sprites disappear starting from the left.

http://i286.photobucket.com/albums/ll95/lacota_rds/LeftMissingTiles.jpg

Other times random sprites disappear.

http://i286.photobucket.com/albums/ll95/lacota_rds/RandomMissingTiles.jpg

It seems to be based on the number of sprites. If I reduce my array to 9x9 I have fewer missing sprites and if I reduce them to 8x8 or fewer I have no missing sprites.

Reducing the LOD has no effect. They are all using the same material.

This is a big problem as I expect to have many more than 100 sprites in my scene. Has anyone else experienced this?