Android :: OpenGL Dropping Triangles

I am doing some very basic drawing of triangles in OpenGL, but I am seeing strange rendering errors. When I draw a textured square (two triangles) part of the square is missing or the texture is stretched or corrupted. When I draw a square with no texture, part of the square is missing sometimes. I do not see a pattern to when it works and when it doesn't. It might be broken one run, then after a back button and rerun, it works the next. The triangle that's missing is not one of the triangles used to draw the square. Rather it is part of the first triangle and part of the second triangle. The triangles are the bottom right half and the top left half of the square, but the part missing is the bottom left half of the square.