Cage that mouse! I had a similar problem with mga200 with hardware
accel enabled. Upgrade had changed the resolution and X did not
recognize all video ram: the latter I think was the problem. Sax2
apparently doesn't allow manual specification of videoram. Someone on
a debian list had suggested deleting the videoram spec and letting the
driver find it. That worked. Of course, your 550 is much more
sophisticated.
Best,
jim bennett
From: Fergus Wilde