when i play my map as a clone or etc it shows a black ground ware ever i walk, but when im not walking there it shows the real ground texure that i made.

Go to Options,then click Video Options and make the terrain texture to low.That should do the trick.This happen to me too sometime.

That is the in-game solution, but if you want to actually make it so you can have the texture visable on the higher settings, there is another way I think. I can't be sure, but I'd suggest making sure every possible MSH, TGA and .option you might need or reference is there in your World folder. Have a "detail" or "bump" texture referenced for each texture in the map editor as well. Also, make sure your .SKY file is not pointing to a TGA that isn't there. Also, certain shipped SKY files have settings that have worked better for me than others. Lastly, clean your map before you munge again.