Cant Boot From Disk


my computer stalls on the "starting os x" screen. it won't let me start up from the disk or in safe mode- its just stuck. ive run "fsck" and it says everything seems to be fine. i would not mind reinstalling tiger- i have everything backed up- but im lost. is there a unix command for booting from the tiger disk that might work? anyone have any other ideas?
Also, try pressing the <option> key during the boot / reboot process.
If a volume (internal, external, or removable) has a bootable system, it will be included in the list displayed.
Once the scan process is completed, and the cursor becomes an arrow, select the desired volume and then click on the '-->' button.