dell gx520 with fc9 won't wake up

[Dave Burns]

I just installed fc9 on a dell gx520, fc6 was on it before and worked
fine. I installed from the live cd, while installing the screen went
to sleep and I could not wake it. I tried again from the beginning and
got through the install, rebooted, turned off services and was doing a
yum install when it again went to sleep and ignores input from mouse &
keyboard. It will ping, but I'd turned off ssh so can't log in that
way.

I googled around and searched the archives, nothing relevant. Or maybe
I'm using the wrong terms.

Any clues you can toss me?

Thanks,
Dave