How do I remove unwanted dark grid lines from my Basic_Graphic_Textures?

Question

Basically, I have been having dark grid lines show up in files I create in Illutrator CS6 as of late.  This particular instance is surrounding a background layout im trying to create.  I select a 650x500 rectangle and apply a patterns fill.  To be specific, Patterns--->Basic Graphics--->Basic_Graphics_Textures-----Diamonds.  No matter what I do, there is a dark grid benath the fill. It shows up in any fill I have been doing lately.
The above image is a layout with 3 layers.  1 white layer(bottom), 1 red/pink layer(middle), and the top layer being the rectangle/diamond fill.
This only happens with pattern fills and with fluid repeating text fills.  Normally, the dark lines are full squares, but in the above image they are only running vertically. Any suggestions would be greatly appreciated.  I'm not sure  if this is just a hardware issue with my graphics card, or if I'm missing something else.

Answer 1

The patterns are for filling space with a repeating pattern but have some problems as you are discovering. Try dragging the swatch for the Diamonds texture from the Swatch panel to a file you have open. You can see how the pattern is created. Notice the overhang on both sides. Does this look like your problem?
By changing the stroke of the line in the Diamonds pattern to 0.25 and replacing the swatch I have to go out to 50% size to see the repeat like this