Comment 2 for bug 715330

Reproduce the issue, log in, and with the system frozen collect the output of dmesg, your /var/log/Xorg.0.log, and your /var/log/kern.log.

Also, avivotool can be used to assist in debugging this issue. avivotool is provided with the radeontool package, so to install it run:

    sudo apt-get install radeontool

After installing it, you run it like this:

    avivotool regs all > regdump_good.txt
    avivotool regs all > regdump_broke.txt

Run it two times. Once when you have a working screen, and once in the broken case (either from the tty console or logged into the sick box remotely). Attach both of those to this bug report.