Resending this as it got linked as a reply to an unreleted post earlier... Added clamping of 16 bit values when copying mode info in "Xserver/Xext/xf86dga2.c" which fixes this bug. Could some take a look and commit to CVS if its all good? https://bugs.freedesktop.org/show_bug.cgi?id=2176 Cheers, James