Dunno. But I always burn stuff at 8x after having troubles.
I haven't done exhaustive testing the way you have, but I have come across some CD drives that haven't liked disks burned at higher speeds that worked fine when the disk was burned at 8x. IIRC, it was often a problem with disks burned using an older version of EzCDCreator.
I read once that the laser power and/or wavelength changed in moving from ~ 8x to higher speeds, but I haven't seen anything like that in a search just now.
Hope you get it resolved - whatever the problem is. I suspect there's a reason for the difference and it's not just digital goblins. :-)
Cheers,
Scott.
