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Whenever I try to restart my Ubuntu either from the command line by typing reboot or in GNOME the computer goes from X to console, starts the shutdown process and then a message saying "[ some number ] Starting new kernel" appears on the screen and the computer goes back to X login screen. I suspect this must have something to do with nvidia drivers, because it seemed to have appeared around the time I bought a new graphic card. Also, when I reboot the second time I see weird graphical artifacts on the screen. When I boot from ubuntu live cd I can reboot just fine. I used jaunty, recently I switched to karmic with no change.

This bug is very annoying, because I have to hard reset my computer in order to reboot. Also not good for the filesystems, I suspect.

Can you suggest a way to debug the cause or if not at least the easiest way to go about reinstalling ubuntu without losing customizations/settings/data?

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From a console window, type sudo shutdown -r now and see if you experience the same behaviour. You may be prompted for your root password. – user3463 Oct 31 '09 at 12:55
    
Tried what you suggested. Seems like with shutdown I go directly to weird artifacts, which I normally see only when I try to reboot the second time. Anyway - same result after this - back to X login. I took a photo of what I see on the screen if anyone is able to make something of that - img266.yfrog.com/i/20091031173927.jpg. – VoY Oct 31 '09 at 16:44
up vote 3 down vote accepted

"this is not a bug, but a feature" :)

Just change the line "LOAD_KEXEC=true" to "LOAD_KEXEC=false" in the file /etc/default/kexec.

The motivation is given in the file "/usr/share/doc/kexec-tools/README.Debian".

The corrupted graphic display is normal when reinitialization of the graphic memory is performed at boot, without cleaning the memory before the display.

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Thanks a lot. You saved me a reinstall, sir :-). – VoY May 23 '10 at 21:13

OK so based on the "artifacts" image you shared, I'm gonna go ahead and blame failing RAM on this. Seriously - it wouldn't hurt to boot up memtest and let it run overnight or over a weekend.

Also, since you're comfortable with installing hardware - make sure everything's seated properly; sometimes cards and RAM are "mostly in" but not all of the way.

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+1 Even if this isn't the problem, this is worth trying anyway! – Yuval Dec 3 '09 at 7:31
    
Good idea, I'll try that. Still, this doesn't seem to happen when I boot from live cd, so that's weird. Also, shutdown (as in turning off the machine) works fine. – VoY Dec 3 '09 at 12:08
    
But even if its failing ram - it's weird that reboot of the machine leads to restart of X. The artifacts appeared the second time I tried to reboot after that happened. I may end up reinstalling the system to be 100% sure, after I try memtest. – VoY Dec 3 '09 at 12:11
    
Well the default run-level is what's bringing X back up, as the machine reboots back up. FOLLOWUP QUESTION: Do you see the exact same characters, the exact same color, in the exact same locations, every time you see those "artifacts"? – pbr Dec 3 '09 at 15:54
    
I think I do, yes. Tried different modules, no change - works using live cd though. Still haven't solved this. – VoY Apr 5 '10 at 22:03

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