We'll have to fiddle with it.
I don't get that problem here, so it will be hard to troubleshoot.

Where does your alphamap live? Is it an entSkin or a mtlSkin?
Could you try adding the "my.tranparent=off" to your action, just in case?

Maybe try adding "zenable=true"

technique ffp_terrain_tex
{
pass P0
{

alphablendenable=false;
zenable=true; //<<<<<<<<<<<<<<<<

If need be can I get a publish of that level and see how it runs on my card?

I'll think on it a bit and get back to you in a Private message.

Eric