For some reason whenever I try to load a vector file into Photoshop from Illustrator without rasterizing it I always get weird lines. Often it's between shapes (which is especially annoying when shapes of the same color rest against each other, giving a line where there should be continuous color) but mostly it's around the edge. I can't seem to figure out why it's doing so. I've tried expanding, joining in pathfinder, etc... but to no avail.
Here's an example of the trouble at its best.