I just recently installed updates from Ubuntu and the system is hosed. I get the Ubuntu screen that flashes real quick then it goes to the Nvidia like cursor. I am pretty sure something is hanging up on startup. I cannot get to a console, cannot do anything but reboot with ctrl alt del. Then I get the briefest flash of the screen but not long enough to see where it was hanging up at. I ran the same updates on this machine, if I could get the old school informitive startup screen instead of the windows like tell you nothing start up screen I might at least know where to start looking. Right now I have zero clue as to what the updates broke. I cannot even get to log files as there's no console, no ssh, nothing.

version is Ubunto 10.4 LTS.

That silly eye-candy boot is Plymouth, I hate that thing. In fact, I am going to uninstall it right now. Hopefully it won't render my OS unusable too.

Anyway, in the good ole days when I used Slackware, I used to be able to halt the boot while the Grub menu was showing, then press 'e' to edit the corresponding boot entry, then add '3' to the end of the kernel line, then press 'b' to boot. That would force a pure command line boot, without the desktop environment. Adding '1' instead of '3' to that line would force single-user mode. Either option should be enough to let you boot the system and do some repair work.

But that was Slackware. Ubuntu adds some interference here and there, like removing Ctrl+Alt+Backspace, so I am not sure that backdoor will be available in Ubuntu. As a last resort, you may want to try a rescue CD like System Rescue CD. There is a USB stick version, too.

Hitting <Esc> at the appropriate time should be sufficient to cajole Plymouth to stop hiding the messages. The commands @lucmove provided are for classic grub - Lucid probably uses grub2; see this. Particularly the "Command Line and Rescue Mode" section - you need to hit the <Shift> key during boot to pop up the boot menu if it is hidden.

And after a little research, I learned that Plymouth cannot be removed. Hideous. Just hideous.

I just tried the tip on this page. It works to the extent that I get a proper boot for adults. But it hangs halfway through. So it doesn't work.