[VanDeKoik]

“You didn’t say what distro you have, btw, and the expression “boot into Gnome” doesn’t actually make sense. By the time Gnome should be coming up, the boot process is well over and the kernel is fully operational — at that point, it’s starting up applications. “

It’s Ubuntu. It goes through some sort of startup process but when the desktop usually appears, I get just a blank screen.

[thulldud]

Probably trouble with the X server. Not having used Ubuntu (loaded it once, didn't like it), I am not going to give detailed help, but I can say that if you can get into a command line, have a look at /var/log/messages, toward the end, you will likely find out what is going wrong.

If you can get the Gnome desktop by booting from a live CD, it's probably a configuration issue. In any case, live CD's usually include a rescue boot option which would allow you to mount the hard drive and edit whatever was broken. But you would find out what needs fixing by looking at /var/log/messages.