Q I have a Samsung 2343BWX monitor that won't work with Ubuntu 8.10. When I boot up with the live CD, the process stops, I get a blank screen and two of the three lights on the top of the keyboard blink on and off. Nothing further happens. The lights that blink are the one above the A and the light to its right with the arrow symbol under it. Initially, I thought the problem might be the video card, so I bought an Nvidia GeForce 6200, but switching the card didn't solve the problem. Then I tried the monitor on a few other computers I use (they have OpenSUSE 11.1, Mandriva 2009 and Fedora 10 installed on them), but it seems to work OK. This monitor also works when I boot Ubuntu 8.04. What do you think the problem is?
A It's highly unlikely that this is anything to do with your monitor, Jim. In fact, we expect you'd see the same symptoms even if you switched your monitor for another. The clue is in the flashing Caps Lock and Scroll Lock keyboard LEDs, which indicate a kernel panic. This is when the kernel encounters an error it cannot deal with - it's similar to the Blue Screen of Death found in a certain proprietary operating system, but usually more informative. In other words, when the kernel hits an error it cannot resolve, it prints debug information to the screen and stops working. The flashing LEDs are an extra indicator should you be unable to see the screen output, as in your situation.
The reason you cannot see the error message is that Ubuntu, in common with most other distros, hides the boot messages behind a splash screen. To remove the splash screen and see the error message, boot from the CD, pressing F6 to display your options when you see the boot menu. Delete the words quiet and splash from here and press Enter to continue the boot. Your computer will still hang with the kernel panic, but this time you'll be able to see what it says. Now plug the error message into your favourite search engine to find a possible solution. Unless you are using some extremely obscure hardware, it's likely someone else has already encountered this problem and the solution is out there.
There are a couple of standard things to try before you hit your search engine, though. First, unplug all unnecessary USB devices. Fairly obviously, you'll still need your keyboard and mouse connected, but any scanners, printers, audio devices and external storage devices can go for now. This doesn't mean you won't be able to use them, only that they're causing a problem for the kernel on the live CD. Once you have the system installed, you can reconnect your devices.
Another common problem is a buggy APIC (Advanced Programmable Interrupt Controller) implementation on your motherboard. You see, some manufacturers are content to do the minimum required to get your board to work with Windows, rather than build it to the specifications. This issue can be avoided by disabling the kernel's APIC support. Press F6 to get the boot options as you did before, remove quiet and splash so you can see what's going on and replace them with noapic. If this works, you can add the noapic option to your boot menu during installation to use it every time, but you should also check whether there's a BIOS update available for your motherboard. Even brand-new motherboards have updates available by the time they reach the shops and these often fix APIC-related problems.