MSI MegaBook? 270 Crashing

With debian, ubuntu and vanilla kernels, many different versions from 2.6.12 to 2.6.19, I see this problem: The machine freezes hard. Usualy the screen turns white, but it could be any other color as well or display stripes. I need to turn off the machine hard. No messages in the syslog, no messages via netconsole. The machine dies immediatly, does no longer respond to ping etc.

My machine is running ubuntu edgy with 64bit kernels and 64bit userland and a few 32bit applications (like mplayer, firefox, flash plugin etc.). The CPU is a AMD Turion MT-40. Reports so far indicate only Turion users are affected, sempron users do not report this problem.

If I run my machine with xen 3.0.2 and kernel 2.6.16 (with xen patches), the machine is 100% stable. So it seems to be a kernel problem. Memtest+ was run for hours without any problem. Also with the normal kernel the machine is very stable, if I watch movies (e.g. mplayer), only edit files, or even stress the kernel with compile operations and other cpu heavy tasks. But once I run GUI applications like konqueror, firefox, thunderbird, kontact, they tend to trigger a crash within few minutes.

Any idea what I can do to get the machine stable (without xen and xen-ified kernels)? Please contact the s270-linux mailing list, or directly Andreas Jellinghaus <aj@dungeon.inka.de>.

I'm attaching config, dmesg, xen dmesg, lspci -vvv and the xorg log file. "good" is 2.6.16.31 with xen 3.0.2, "bad" is running a vanilla linux kernel 2.6.19.

I'm running the machine with the open source xorg radeon driver. I don't have the ati fglrx or any modules or libraries for it installed. But earlies I tested the stability with the fglrx driver (ubuntu dapper and edgy packages) and the plain xorg vesa driver, and both are instable as well.