I've got a weeks-young install of 13.04 (184.108.40.206) and the computer has been powered on for a week. I turned it off for the night and now it freezes during boot.
I have already checked this seemingly mandatory post as well as this one but I couldn't find a solution. This one also looked promising but I can't get my machine into read/write mode because recovery isn't working and
drop to shell only gives me a read-only system. Setting radeon.modeset=0 also ends in a freeze.
At this point, my computer is completely unusable and I have to run off a liveCD to write this question.
How can I identify the problem, and how can I solve it?
This is not an Nvidia problem, as the machine has a Radeon HD 5450 card. IIRC it's running with
-updates and not built-in because then I wouldn't get my 1280x1024 resolution.
As far as I recall, I have not fiddled with any bits, certainly none at the system- or device level. I assume that installing user apps like Gimp can't have any impact.
normal boot: brief purple screen, then a text-mode TTY1 login prompt flashes on just before Ubuntu (tries to) load the GUI. Except that now, the GUI doesn't arrive: the TTY1 text-mode screen disappears, there's an underscore cursor which does not blink, and then nothing more ever happens. Neither Ctrl-Alt-Del nor Ctrl-Alt-F2 or -F7 work. It seems frozen and requires a hardware reset.
recovery boot: the GRUB screens take a long time to show; I'm used to the sub-screens being shown instantly but now there's a delay of maybe 10-20 seconds before the "advanced options" screen is shown. No idea why, nor whether this is related to the boot problem.
After loading the recovery mode:
several of the recovery options start out with FSCK, and I often get
mountall: fsck /boot  terminated with status 1
on the screen, and after that nothing more happens. Sometimes I get
cleanresponse instead, but still nothing more happens. Either way, the only keyboard input it will accept is Ctrl-Alt-Del but this does not reboot the machine right away! Instead I see a graphical notice
the system is running in low-graphics modealthough ironically, this message is displayed at 1600x1200 pixels which my monitor can't handle so it puts its own warning message in the middle and I can't see the rest of the GUI output. Then, before I can react, it reboots.
failsafeX has the same problem as the normal boot: it simply freezes after TTY1.
Hitting Ctrl-Alt-F1 or -F2 or -F7 at various stages doesn't do anything at all. This makes me think the machine is really frozen, rather than just working fine but without screen output.
editing GRUB's normal boot entry to remove
splash quiet, and to add
noapic nolapic nomodesetdoesn't help either. Same situation. Same also when doing that on the recovery mode's boot entry.
Using the recovery mode to boot the previous kernel version (220.127.116.11) also has the exact same behavior.