Ocasional but Consistent Horizontal Lines On Edges of Diced background

[richicon]

Hi
we have a strange issue on a 13-inch MacBook Pro (non retina).
We're getting horizontal lines (image attached) on the boundaries of the tiles when running fullscreen.
Looking at the atlas texture I can see that the lines are caused by bleeding from adjacent tiles.
However I've checked, and,
pad Method Is extend
it is point sampled
uncompressed
there is no antialiasing
mip maps are disabled
these settings are matched in the atlas texture.
the resolution of the mac's screen is 1280x800
the game is maintaining a pixel perfect resolution of 960x540

the issue does not occur on other backgrounds in the same SpriteCollection, although the issue does occur on another level with a different sprite collection.
Its fine on PC and on another mac that we have tested it on.
setting pc's and another mac to 1280x800 does not recreate the issue even when using the same package on the other mac as the problem mac
It doesn't happen on all backgrounds, although they are all diced
It doesn't seem to happen on the foreground tilemap, which is again sharing the same spritecollection and atlas.
the sprite collection is stored in a single atlas

I'm baffled, anyone had a similar problem or any idea why its happening,

thanks

[unikronsoftware]

It implies that something is causing the hardware to sample offset. Try adding 1 pixel padding to the sprite collection - the default is none when point sampled. This should eliminate that.

Different hardware filters differently - check the gfx hardware spec on the machine it breaks on, is it different to the mac that works?