Comment 4 for bug 735126

If you plug in an ethernet cable and then boot, are you able to ssh in? If so, you can gather the log files that way. If not, then you may have a deeper kernel bug at work.

Without knowing the errors being encountered it's hard to guess what might be wrong; I have two -ati systems I regularly test natty on and neither freezes in this fashion, so I don't reproduce the problem myself.