Hi. I have the problem described in this thread: http://forums.adobe.com/thread/1055012 The problem is that neither "sudo gdm service restart" nor "shutdown 0" will work after the flash player crashes sequentially crashing X Window Manager. I have no choice but to long press the power button of my laptop to force turn it off. This will definitely destroy my hard disk in the future :-( Is there no other way to force restart X? The symptoms are weird. I have 2 monitors, after flash player crashes, sometimes X will partially survive and one of my monitors will turn blank and the other is still functional, which then i try to run "sudo gdm service restart". X attempts to restart but never comes back up rendering my computer useless. THen i try logging in remotely and then doing "shutdown 0", it informs me it's shutting down and i lose connection to the computer. But my computer is still running, it never turns off. i can't do anything to turn it off or restart. this problem is really killing my productivity, in my company i'm the only flash developer working on linux :-(

Ctrl Alt F2
Will put you into another shell where you can log in and kill X.

Example
or
Ctrl Alt Backspace
May kill X too

http://linux.die.net/man/2/kill
http://linux.die.net/man/1/pkill

hi teckk.

thanks for your response but killing won't do the job. After killing X remotely we lose complete control of the machine and have no other way but to long press the power button to restart. we found out yesterday with dmesg that it was some sort of problem in the nvidia driver that it starts to go berserk. the only workaround we found was to disable hardware acceleration of the flash player.

If you can get in remotely to issue a shutdown then have you tried reboot instead? I've had problems where shutdown doesn't fully shut the PC down but reboot will work.
I know it's not a solution, but it should stop you having to power off while you wait for one.