If you're using OS X, get rid of Nortons.
Use the Activity Monitor in your Utility folder, if it will open, to quit any Norton process.
Then Repair Permissions using Disk Utility in the Utility folder.
Then 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 (#).
You're now in single-user mode.
Now that you're at the # prompt, here's how to run fsck:
1. Type: "fsck -y" (that's fsck-space-minus-y) (without the quotes)
(If you're running Panther, v 10.3, then type this "fsck -f"
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 running fsck. 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.