Unity 4 standard assets not playing well with Unity 5

Hi all,

I've run into a few issues after upgrading my project to Unity 5. My project is using some of the Standard Assets included in previous versions of Unity, including some of the standard skyboxes. After upgrading to Unity 5, these skyboxes now appear in my editor with splotches of black where the clouds are supposed to be. Why does this happen and how can I fix it?

Also, the Simple Water Prefab behaves erratically. Even though its material is properly assigned, it does not show unless I drop in a second instance of the prefab, and then the texture flashes on and off during gameplay. Has anyone experienced something similar? I might have to look for some sort of replacement for the simple water if I can't fix it. Any help would be greatly appreciated.