Could be many things, we should start with this...
"Try Disk Utility
1. Insert the Mac OS X Install disc, then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu at top of the screen. (In Mac OS X 10.4 or later, you must select your language first.)
*Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.*
3. Click the First Aid tab.
4. Select your Mac OS X volume.
5. Click Repair Disk, (not Repair Permissions). Disk Utility checks and repairs the disk."
Then try a Safe Boot, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, reboot when it completes.
(Safe boot may stay on the gray radian for a long time, let it go, it's trying to repair the Hard Drive.)
If perchance you can't find your install Disc, at least try it from the Safe Boot part onward.
A reinstall of the OS may be needed, bit secondly try...
1058 Combo Update, 10.5.8...
Repair Permissions afterwords, reboot.
Booted from the OS 10.5.1 disk, got to First Aid tab in Disk Utility, selected my
HD, clicked Repair Disk and got error message "First Aid Failed- Filesystem verify
or repair failed. invalid key length - volume check failed"
Now I can't restart from my HD and the 10.5.1 boot disk won't eject either. Restart
efforts gives me a horn while holding start button. I can still start using the boot disk
but choosing restart from another source doesn't work.
There used to be a pin release to eject a disc but I don't see any.
To eject the Disc, hold Mouse button down while booting, also hold alt or Option key to see bootup choices.
The Disk need Repair.
Does it boot to Single User Mode, CMD+s keys at bootup, if so try...
Repeat until it shows no errors fixed.
(Space between fsck AND -fy important).
Resolve startup issues and perform disk maintenance with Disk Utility and fsck...
You may need something stronger.
You must repair the HD, if Disk Utility or fsck should fail to repair it, your best bet is DiskWarrior from Alsoft, you'll need the CD to boot from if you don't have another boot drive...
Your best bet is DiskWarrior, you need the CD/DVD though.
But others that may work…