Installer Issues via Installer -- Not for global upgrades or upgrading individual packages -- ONLY ISSUES WITH INSTALLATION OF THE OS -- Can't get Sabayon installed, than post here, otherwise use correct forums
It's an ati related issue j think... the same here both with 3.4a and 3.4e and an ati 9700pro...
It's related to ati driver, so you can fix booting with radeon driver instead.
J myself did:
sudo nano /etc/X11/xorg.conf
Look for driver=fglrx and substitute with driver=radeon
save and exit
type "gdm" and login
This worked for me both in live dvd and in installed system.