Please read the first post again. The problem is that system doesn't boot at all without
any proprietary nvidia modules installed. Bug in nouveau kernel module prevents system from booting with default flags. There are two solutions:
1. Install proprietary driver. Installing nvidia driver disables nouveau, and system works fine.
2. Add "acpi=off noapic" to /etc/default/grub - this will let system boot and work with nouveau, but the screen resolution may be wrong.