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I am using Karmic Koala (Ubuntu 9.10) to my surprise, every so often, the screen freezes completely in that it does not respond, even though I can move the mouse about ... nothing responds when I click on it. I cant do anything until I reboot the machine (this [forced reboots] is the reason why I am moving away from Windows - to find this happening on my beloved Linux, is more painful than I care to admit)

I have not been able to reproduce this sufficiently enough - so it seems to be probably an erratic bug. Most of the time when the screen freeze happens, I am running a combination of one or more of these (Firefox 3.5.7, gEdit, Console, Qt Creator [1.2.1])

Is this a known bug, has someone come accross this before, whats the fix?

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migrated from serverfault.com Jan 14 '10 at 12:43

This question came from our site for professional system and network administrators.

    
Is this standard Ubuntu Desktop 9.10? If so you might get better answers on SuperUser. –  Anonymous Jan 14 '10 at 9:23

4 Answers 4

If this was also occuring on Windows, could there possibly be some kind of hardware issue? (Faulty RAM or Video Card) which is causing the system to lock up like it does.

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No, this only started when I moved to Ubuntu –  Anonymous Jan 14 '10 at 12:20

i also had some strange issues with ubuntu the last days. after an update everything is now running normal again.

just get the last updates and restart your system. although the restart is not really necessary when you look at the updates, it helped. should be the last reboot for some time. ;)

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Can you switch to another console (press Ctrl+Alt+F1) login and do a top to see what is happening? If nothing stands out in the 'top' list, try killing any suspect apps and see if it unfreezes after killing a particular app. (The three you mentioned sound like good candidates.)

The easiest way is to find their PID using ps aux | grep <part of the app name>. (E.g. ps aux | grep qt will give you a list of everything with 'qt' in the name.) Choose the one you want to kill then use that PID number with the kill command. (E.g. if firefox had a PID of 2345 then start with kill 2345 and if it's still alive use kill -9 2345.) Use Ctrl+Alt+F7 to switch back from the console to your main (hopefully unfrozen) X GUI session. If the computer is still frozen then repeat with the next "suspect" app.

If it is always only one app that is causing the freeze then it might be a good idea to uninstall-purge-reinstall it; if it still continues then put in a support request on the app's forum/mailing list.

BTW If you can't get the above to work, what happens if you Alt+PrtScr+K after a freeze? Does it kill everything running in your current X session and restart X, it or is everything still completely locked up?

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That sounds like a goos logical way to approach the problem - unfortunately (infact, I tried to switch to another console the last time this happened, to see if I could identify the rogue process) - however the entire screen is unresponsive (i.e. widgets) - the only thing that responds is the mouse. the cursor is visible, and moves, but nothing happens when I click (Hmmm, makes me wonder if its the mouse - its quite an old mouse - but I dont want to go out and buy a new mouse if thats not the problem) –  Anonymous Jan 14 '10 at 12:24
    
correction: *goos => good (I think my brain is telling me its time for another cup of steaming black coffee) –  Anonymous Jan 14 '10 at 12:25
    
@Anonymous: Switching to tty has nothing todo with the GUI...in fact, kernel-commands (like Ctrl+Alt+F1 or Alt+Print+K (restart X)) are even working if the whole X-Server is frozen and crashed, because they're caught on kernel level. –  Bobby Jan 14 '10 at 14:51

Try Alt-F1, then Alt-F2 combination. Your screen unblocked?

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