A common issue with Unity is the suspend feature, which reboots some computers when resuming. I have figured out how to fix it, tested it, and it works. You change line 11 of /etc/default/grub to:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_sleep=nonvs"
I would like to post this as an update for future Ubuntu versions. How do I do this?
More info about the changes: Sony Vaio FW350 reboots instead of waking up after sleep/suspend