Right. Since nothing else works, try a Virtual setting. Forget where it's done(in with the video card stuff I think), but the syntax is

Virtual xdim ydim
e.g. Virtual 1600 900

Then you can really mess things up :-)).

man xorg.conf says Virtual goes in the display subsection of Screen: Yet it still didn't change anything. The file is supposed to be named "video.conf" and placed in the "/etc/X11/xorg.conf.d/" directory, right? Want to make sure I didn't miss something obvious and I'm at fault.

Hmmm.

Presuming you boot to X (runlevel 4 or 5 usually) try going to runlevel 3 (init 3 as root might do it).Then run
See why it's kicking the modes out and notice warnings and errors. It's chucking out your chosen configuration and it's nice sometimes and tells you why.

Well I ran init 3 and startx, but realized I didn't have the external monitor plugged in at the time, so I plugged it in and restarted, but now I can't log in to my system. With the monitor plugged in it says something about being "unable to write bytes: broken pipe", and without it just unmounts everything. Either way it takes me right back to the login screen. Sorry I can't provide more detail on the messages, they flash for about half a second before taking me back to the login page. I already used my liveUSB to remove the video.conf file in case that was messing it up, but apparently something else is. All I recall doing last time I was logged in was reading this thread, installing updates, and then trying the init 3 thing, so I'm assuming it's the latter that's causing problems. Netbook is unusable until I get this fixed since I'm not dual-booting.

Unless things have changed, Ubuntu's default runlevel 3 is the same graphical mode as runlevel 5 (unlike Fedora and many other distros, in which runlevel 3 is text mode).

Yeah when I ran startx after doing init 3 it said that x was already running, but after restarting now I can't log in so I'm unsure on how to progress. I can still log in as a guest or through tty though if that helps.

Ended up just re-installing, think I'm going to call it quits on trying to get this to work, it's not absolutely necessary by any stretch of the word, and re-downloading all the packages I want after wiping is time consuming. I appreciate the help anyway though, learned a few things at least.

Sorry, my bad. You need a text mode for that, to run startx. If I were reinstalling, I'd reinstall something else. Hope you're sorted.