At random times, Ubuntu 10.04 freezes, and I have to do a hard shutdown. It was upgraded from 9.10 which didn't freeze. First, is this is common problem with a quick answer, and if not, what can I do to diagnose it? I've tried checking application/kernel logs, but nothing gives me a clue as to what caused the problem. My guess, is that since the OS froze, no logs could be updated.

Ideas?

SOLUTION:

Solved it.

My particular problem was my graphics card (integrated Radeon 9000 series). netconsole revealed I was getting the error: "reserve failed for wait". After trial-and-error, I manually configured my video card and disabled hardware acceleration. Completely fixed the issue.

Here is what I did:

Manually Created xorg.conf

Ubuntu automatically configures xorg.conf and doesn't use a file. To edit this file, you have to tell Ubuntu to explicitly create one and then edit it. Here are the steps:

1. Restart system
2. Hold Shift as GRUB boots
3. Select root terminal in GRUB login menu
4. Execute: X -config xorg.conf.new
5. Copy: cp xorg.conf.new /etc/X11/xorg.conf

Disable Hardware Acceleration

The following is specific to my Radeon card, but I'm sure other cards have a similar setup.

1. Edit xorg.conf
2. Find "Device" section for graphics card
3. Uncomment "NoAccel" option and set to "True"
4. Save + reboot

Hope that helps.