me too (X4.0.2 on iBook Firewire)
I also upgraded my iBook Firewire to sid, and I have the same pb as Michael Hope
and Christian Pernegger.
Pitch is also reported as 832. I tried disabling Acceleration, changing colour
depths, "ati" and "r128" as the name of the driver. Using the fbdev driver works
Could it be that the old ati driver (for mach64 cards) wants a pitch multiple of
64 to use the acceleration, and it's leaked to the r128 driver ? I mean that the
r128 part of the driver is using a way of calculating the pitch that is
different from what it was before.