Ubuntu won't start after the updates

I dual boot WIn7 and Ubuntu 12.10, and after installing Ubuntu last night, all I did was install all 392 updates from the store program, install google chrome for Ubuntu (not chromium), and install JDK7 and Minecraft.jar. I noticed while doing that sometimes my screen would freeze for a second, black out, then back up and say something like compwiz or something crashed then I told it to keep it closed, but it kept doing that sporadically, and I also noticed Minecraft was unusually sluggish with the same settings even though my hardware is the same (maybe a driver issue in Ubuntu idk, could be about anything)

Today I came in, tried to boot, and got a bunch of error i/o stuff in a black screen, saw it was something about having a disc in the drive, took the disc out, restarted, and now it just black screens on the login and has this tiny [ok] in the top center of my screen and a little flashing cursor. I can't interact with the computer at all and must give it a hard shut down.

Is 12.10 like an experimental version? I want a stable copy of Ubuntu. I was hoping to give this OS another try after updates rendered my laptop to suffering from error messages about "System errors" popping up time and time again.

So..um...help!