[Beta 3] More than 4 textures per terrain square go crazy

Hopefully this hasn't been mentioned yet, I couldn't find it. When applying textures to the terrain with a base texture, detail texture, and normal/parallax map, if you have more than 4 on one square it all seems to get mixed up. There seems to be a pattern of sorts to it, but I'm having a hard time picking it out.

Here are some pics with terrain debug view on so you can see how it makes a perfect outline with the terrain squares.

First pic is with 1 solid texture laid down and i painted on 3 new spots. Second pic is what happens when I introduce a 4th spot.



This set is the same test repeated, but with a few different textures. As you can see, the effect is the same, but on different textures. Which textures I use to paint the spots seems to affect which other textures get screwed up, and how.







My system specs are 2 ATI HD4870's, running in Crossfire, 8GB RAM, Windows Vista x64 and it does this to me in an unmodified Beta 3 as well.