I have discussed this problem before, but now I just made a new and very fast capx sample - you should notice the problem on any game you make with tiled backgrounds.
I know you just say it's a graphics driver problem - but it's not. It's present on any computer and other commercial games deffinately don't have this issue! I have tried this on various AMD and Nvidia gfx and on both AMD and Intel PC. Unfortunately the same problem is present.
Try the capx and notice the ugly lines around the top dirt tiles and in the clouds.
On this sample - pixel rounding is even on - but it doesn't make any difference besides making the movement less smooth.
Also notice that a tiles made like a sprites (like the dirt corners) doesn't have the problem when pushed against a tiled background tile. The it looks as you would expect it look.
Actually this problem is worse now than it was before around R100 or maybe R102. I had the problem when using R95, but then it disapeared in some of the later version and then got back around R100-R102.
I have used so much time trying to eliminate the issue - but nobody seems to notice it.