LinuxQuestions.org - Issues loading desktop with multiple distros

I'm sorry this post is so confusing; I have a little bit of experience with Linux but not enough to know what happened or how to find out what the problem is. If there's something I could do to make it easier for whoever is reading this to help me, tell me and I'd be happy to, or if I missed a FAQ go ahead and yell at me :P.

I recently installed Ubuntu, got through the install fine, and then had it dual-booting with Windows XP. However, whenever I would boot to it (any of the options for it in LILO), I would get to the login screen, then after I logged in and it was trying to load the desktop (I think it was Gnome) it would just hang, and I would have to do a hard restart. I have had the exact same problem in Mandriva (set to load KDE) and Kubuntu.

The weird thing is, I installed Slackware off of an old CD I had (probably a year old at least, I'm not sure what kernel or what version it is) and it boots up fine. The only reason I can think of is that Slackware has the video card configuration options in the installation (I have a GeForce 7800 GT and it seems to work using the default GeForce drivers in Slackware). I tried installing the driver off of NVidia's website in Mandriva (I think, it was the only one that had a failsafe option in the boot loader that gave me a CLI), but the driver told me I needed to type telinit 3 to continue the installation, and every time I have done that the shell starts acting really strange (I try to login as root to install, but when I type "root" at the login prompt it comes out rroooot or something, and then I can't type anything else normally). I'm not sure what else to try that might fix the problem, since I can't even load a working installation, even though the graphics look nice during all the installs (except Slackware's obviously).