I have exact same problem - also happens same place if I attempt SP2. ALSO, I had external 500gb USB HD and 4gb in machine, so unplugged USB HD, and removed 2gb. Still reboots.
Also, I had to put 2gb back into mach to get past "Resuming Windows..." then turn hibernation OFF, to get machine to stop "resuming windows...", then remove the 2gb again to reboot.
After that I still have the reboot problem.
Any clues ?