1. boot ubuntu jaunty final version on one of the affected systems
2. run "sudo apt-get install compizconfig-settings-manager"
3. launch the settings manager from system::preferences and activate the ring switcher plugin
4. hold down SUPER+TAB so that the ring spins around full speed
5. xorg SEGV after like 2-3 seconds

Affected cards include:

01:00.0 VGA compatible controller [0300]: ATI Technologies Inc RV380 [Radeon X600 (PCIE)] [1002:5b62]

and also:

01:00.0 VGA compatible controller [0300]: ATI Technologies Inc RV350 AP [Radeon 9600] [1002:4150]


Probably tons of other ATI cards are affected.

Complete logs including dmesg, lspci, xorg.log and whatnot for this crash on these two systems are available in the downstream bug report here:
https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/368049

Backtrace from xorg.log.old was:
0: /usr/X11R6/bin/X(xorg_backtrace+0x3b) [0x813518b]
1: /usr/X11R6/bin/X(xf86SigHandler+0x55) [0x80c7be5]
2: [0xb7f6f400]
3: /usr/lib/dri/r300_dri.so(_mesa_update_state_locked+0x832) [0xad3fa152]
4: /usr/lib/dri/r300_dri.so(_mesa_update_state+0x2a) [0xad3fa28a]
5: /usr/lib/dri/r300_dri.so(_mesa_GetIntegerv+0x278) [0xad4cc0c8]
6: /usr/lib/xorg/modules/extensions//libglx.so [0xb78f6132]
7: /usr/lib/xorg/modules/extensions//libglx.so [0xb78e82e8]
8: /usr/lib/xorg/modules/extensions//libglx.so [0xb78e71a7]
9: /usr/lib/xorg/modules/extensions//libglx.so [0xb78ebd6a]
10: /usr/X11R6/bin/X(Dispatch+0x33f) [0x808d57f]
11: /usr/X11R6/bin/X(main+0x3bd) [0x80722ed]
12: /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe5) [0xb7b39775]
13: /usr/X11R6/bin/X [0x80717a1]