On Wed, Jan 9, 2013 at 5:26 AM, Michel Dänzer <daenzer@debian.org> wrote: >> [ 2478.775] (II) RADEON(0): KMS Color Tiling: enabled > > Does > > Option "ColorTiling" "off" > > prevent the problem? (Verify in the log file that the option takes > effect) No, but when the problem did appear it went away much quicker than before. The letters were only weird for a few seconds rather than a few minutes.