Comment 4 for bug 546578

radeontool can be used to assist in debugging issues where the screen blanks like this. After installing it, you run it like this:

    radeontool regmatch '*' > regdump_good.txt

    radeontool regmatch '*' > regdump_broke.txt

Run it two times. Once when you have a good, working screen (for any driver including -vesa), and once in the broken case (either from the tty console or logged into the sick box remotely).