Comment 13 for bug 191613

Many sources are now showing that using the 64bit version of Ubuntu and adding "ec_intr=0" before "ro splash" in the /boot/grub/menu.lst file.

Before it looks something like this:
kernel /boot/vmlinuz-2.6.22-14-generic root=/dev/sda1 ro quiet

Change it to look similar to this:
kernel /boot/vmlinuz-2.6.22-14-generic root=/dev/sda1 ec_intr=0 ro quiet

In other words, don't change anything but adding "ec_intr=0" after the root=/dev/sdaX

For more information about this fix see this forum post: http://ubuntuforums.org/showthread.php?t=609722&page=3

The system they are referencing is the System76 Darter Ultra 2, which is based on the i965 chipset.