First, I tried installing Ubuntu Server 11.04 on an older PC of mine in order to make it a file/ftp and web server. The installation went fine, but when I tried booting I only got a bunch of white lanes splashed across the display. It isn't frozen, since I can see the HD is showing signs of life during boot and after. After wasting two days on this, I decided I'd try my luck with the Desktop edition instead.
I was able to set everything up as I wanted with it, but the issue persisted - if I ctrl + alt + f12 I still get that same garbled, white lines screen. I know it is working, as I can access it remotely (smb, ftp or http). The same thing happens on boot as well - no Ubuntu splash or anything - either a black screen or a mess of random white pixels.
Installing or removing drivers doesn't make a difference. The monitor is an old CRT, don't know the exact model. It's maximum resolution is 1600x1200. The graphic card is an nVidia GeForce 7100 GS (64mb).