Hello,
I have a Compulab fit-PC2 running Ubuntu Jaunty, and its graphics chip is the Intel GMA-500. I am using the Poulsbo driver (xserver-xorg-video-psb 0.31.0-0ubuntu1~904um1 with psb-modules 4.41.1-0ubuntu1~904um1) from Launchpad's Ubuntu Mobile PPA site. However, I keep running into troubles with Xorg (xserver-xorg 7.4~5ubuntu18), and now it seems more often than not that I keep seeing Xorg spontaneously freeze. I assume that the crashes occur under heavy loads (e.g. when compiling a program or frequently opening and closing or switching windows). The display becomes frozen, but you can still move the mouse pointer, and the machine is still remotely accessible via SSH.
As you can tell in the attached file containing the strace output of Xorg, the freeze begins when the ioctl() function starts repeatedly returning -1 (EAGAIN, which means "Try again" or "Resource temporarily unavailable"), and if I try to kill the Xorg server by calling 'sudo kill -9 $(ps -C Xorg -o pid=)', the display becomes completely frozen (i.e. you cannot move the mouse pointer as well) and the whole machine freezes (as evidenced in an SSH connection on a remote machine where you cannot kill the SSH client by pressing Ctrl+C or type anything in the terminal). There is no indication in the logs that a kernel oops related to this problem occurred.
I realized that my trouble with freezing was dued to poulsbo 3d driver, so I removed that and I have no more freeze even running a -13 kernel.