I would first recommend booting off your installation media into Single-User mode, then verifying your "disks" are accessible via the 'format
Odds are good that you have setup a few "Logical Volumes" in the G7's RAID Controller, and that Solaris is not able to properly read these volumes.
From within Single-User Mode, you should be able to test this with the following command;
installboot /usr/platform/'uname -m'/lib/fs/ufs/bootblk /dev/dsk/c0t0d0s0
(Verify that you actually *have* a /dev/dsk/c0t0d0s0
If *that* fails, then get a newer version of Solaris 10 from Oracle (example, if you're using "Update 1" go get the latest, "Update 10")