Question: I am using Ubuntu 10.04 LTS, dual boot with Windows 7 on ThinkPad T400, I followed Ubuntu update hints and installed some update for my ATI Radeon graphic card, but when I boot to Ubuntu (means I can still load GRUB), the screen goes to blank and no matter what key stroke, I can not get any responds. I can't even open a terminal. 

However when I hit the power button, the computer would pop out the Ubuntu shutdown screen briefly and shut down.

I figure out I should delete the updates package for my graphic card, but I don't even get a chance to go to text terminal, please help me!

Answer: 
I got into the same "blank screen on startup" problem on my T400, after installing the suggested ATI driver. This notebook has 2 graphics chips, and the OS can switch / choose between them.
I could resolve the problem by adjusting two BIOS settings (hit F1 after power-on"):

1. Config > Display > Graphics Device: Discrete Graphics
2. Config > Display > OS Detection for Switchable Graphics: Disabled
One approach is to disable quiet in the boot options and read the debug messages to see how far you get in the boot process. 

If this doesn't work then to toubleshoot, you might want to boot to recovery console or runlevel 1, chroot appropriately, and init 3. This will get most of your stuff loaded and let you see if you are having a service hang. 

This should cover the possibility that some service or other is hanging during initialization. 

I really doubt it's a "bad" driver in current stable. 

You could just need to generate a new plymouth or xwindows config. Generating a new xorg.conf and testing is covered [here](http://ubuntuforums.org/showthread.php?t=1437980). Plymouth might black your screen for a bit, but it should pass if you get to fully booted. 

I thought I had a similar problem once, and it was a plymouth glitch that blanked the screen combined with a fsck due to the number of times the disk is mounted. You could try pressing [c] to cancel the disk check in case it's occurring or manually fsck your drives from recovery console to eliminate this possibility.