Q: MacBook starts to boot and then has the "no" symbol, (circle with line through it).  Tried to reboot in safe mode and got the same thing.  Ideas?

Something is messed up with the Disk.

"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 the 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 Utility checks and repairs the disk."

http://docs.info.apple.com/article.html?artnum=106214

See Mac OS X: "Broken folder" icon, prohibitory sign, or kernel panic when computer starts

http://docs.info.apple.com/article.html?artnum=106805

 Cheers, Tom