HD Texture Pack.... Fail? [Please Help] [Pictures Included]

Sooo... I was on my way making a texture pack (32x32), I have made a few blocks, and decided to test them out in a game! It turns out, most of the blocks have lines through them which are invisible, or part of another block. I THINK it has to do something when I saved the terrain.png (I am using Gimp) so if anyone can help that would be amazing. I have some pictures including my problem.





Terrain
To prove there are no invisible lines or other textures in the blocks:



Please help.