Try downloading http://www.opensolaris.org/os/downloads/ Solaris Express Community Edition ? CD | DVD (snv_b84) from the download page and the burn the iso uave and boot the dvd or cd pick second option on the boot menu for Solaris Express Community Edition
thyen log into root and run prtdiag -pv and post the output if you still have issues with the graphics. This message posted from opensolaris.org
