There is a workaround that is working in my case and avoids hanged shutdowns that could damage the filesystems.
I modified /etc/acpi/events/powerbtn so when the power button is pressed it launches a custom script to do the shutdown that basically stops lightdm, kills processes from users, waits 30 seconds and then does the shutdown. Now to shutdown I just close the session and then I press the power button, using this procedure I have avoided the kernel panics during the last month. In case this can be useful to others experiencing the same problem here are the contents of both files: #### Contents of /etc/acpi/events/powerbtn event=button[ /]power action=/etc/acpi/powerbtn_custom.sh #### Contents of /etc/acpi/powerbtn_custom.sh #!/bin/sh # /etc/acpi/powerbtn.sh # Initiates a shutdown when the power putton has been # pressed. # Stop lightdm service lightdm stop # Stop vmware service vmware stop # Kill all user processes that could be left behind by the desktop environment USERS=`awk -F: '{if ($3>=1000) {print $1} }' /etc/passwd` for user in $USERS; do killall -u $user done # Safely unmount /mnt mount points (just in case something goes wrong) FILESYSTEMS=`mount -t ext3,ext4,xfs,btrfs|awk '{print $3}'|grep "^/mnt"` for fs in $FILESYSTEMS; do umount $fs done # Sleep 30 seconds just in case: it seems to help avoiding hangups sleep 30 # Shutdown /sbin/shutdown -h now "Power button pressed" -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/750437 Title: fglrx hard lockup on shutdown To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/fglrx-installer/+bug/750437/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs