Try running both the Disk repair and Permission repair from the OS CD. I would also run fsck.
To run fsck, you first need to start up your Mac in single-user mode. Here's how:
1. Restart your Mac.
2. Immediately press and hold the Command and "S" keys.
You'll see a bunch of text begin scrolling on your screen. In a few more seconds, you'll see the Unix command line prompt (#).
Congratulations.You're now in single-user mode. I bet you've never seen your Mac screen look like that before. (I wish I could show you a screen shot of it, but as far as I can tell, it's not possible. And photos of it are ugly.)
Now that you're at the # prompt, here's how to run fsck:
1. Type: "fsck -y" (that's fsck-space-minus-y).
2. Press Return.
The fsck utility will blast some text onto your screen. If there's damage to your disk, you'll see a message that says:
***** FILE SYSTEM WAS MODIFIED *****
If you see this message--and this is extremely important--repeat Steps 1 and 2 again and again until that message no longer appears. It is normal to have to run fsck more than once -- the first run's repairs often uncover additional problems..
When fsck finally reports that no problems were found, and the # prompt reappears:
3. Type: "reboot" to restart,
or type "exit" to start up without rebooting.
4. Press Return.
Your Mac should proceed to start up normally to the login window or the Finder.