After installing nvidia drivers in any way(manual, envy, restricted driver manager), configuring Xorg.conf and rebooting my X wouldn't start with error from the topic.
Now, when I installed drivers in recovery mode(with 'telinit 3') my X won't start, I'll get black screen and freeze. I can't even get to console when the freeze occurs.
I have acpi=off and I can't really turn it on, because otherwise ubuntu(and any other distro I tried) will hang as soon as it loads.
More detailed information about everything can be found there: