r300 microcode seems to get 'reloaded' and crashes X

Binary package hint: xserver-xorg-video-ati

Hello,
this is a random bug I seem to experience on my system. I haven't found a way to reproduce it every time, but it has already happened various times.

Software: Ubuntu 6.10 32bit, 2.6.17-11-generic kernel, fully updated system.
Hardware: Dell Latitude D810, Pentium M, 1GB RAM, Ati Mobility Radeon X600 128MB

This might be an upstream bug or a kernel/DRM bug.

I'm using the free r300 driver, no fglrx installed; glxinfo shows DRI working properly, and I don't experience problem with 3D software either. I'm not using Compiz or other 'exotic' piece of software.

But, sometimes, with no apparent reason (most of the times I do not start a 3D software, nor do I start a new software at all when this bug triggers!), something strange happens; it seems that the system tries to 'reload' the DRM driver even though it's already loaded.

This is what I see in /var/log/messages at the 'normal' system startup (X starts automatically):

Mar 28 10:33:03 latitude kernel: [ 3006.483000] [drm] Setting GART location based on new memory map
Mar 28 10:33:03 latitude kernel: [ 3006.484000] [drm] Loading R300 Microcode
Mar 28 10:33:03 latitude kernel: [ 3006.484000] [drm] writeback test succeeded in 1 usecs

and things go perfectly. When this bug happens, my whole X is completely locked; I can move the mouse but I get no response from the screen whatsoever, I need to switch to a console and restart X/gdm to get my system working again. In the mean time, I find various lines like those in /var/log/messages:

Mar 28 10:31:48 latitude kernel: [ 2931.758000] [drm] Loading R300 Microcode
Mar 28 10:32:45 latitude kernel: [ 2988.780000] [drm] Loading R300 Microcode

About once every minute or so till I restart gdm - even though the same message was already there in the log for the very same X session.