Create a path snapped to pixel.
Disable align to pixel on all paths.
Select the entire path and create a new symbol with align to pixel disabled OR (it makes no difference) create a new symbol from a temporary path and then paste in place. Everything looks good. Paths are aligned to pixel.
Exit isolation symbol mode.
Go back into isolation mode.
>>>>>>>>>>>> Viola, all your paths are offset by miniscule ammounts causing them to bleed into each other. You can't realign your paths with snap to pixel because snap to pixel doesn't work for a set of paths because it snaps to a random path or something.
Or you can enable align to pixel and have the copy paste completely mess up your paths.
Why would you expand paths that are snapped to pixel by a miniscule ammount on a paste?
Is this fixed in CS6?
Align to pixel grid is the most dangerous "feature" in Illustrator. Thanks for never mentioning that it's guarunteed to screw your paths up in unexpected ways. So apparently you can set Align to pixel grid on a path in a symbol. Then go in to reedit the symbol. Exit out of isolation mode and have the path be modified for apparently no reason.