Hold down the 'C' key while booting to force a boot from the CD. Also, you can hold down the 'Option' key to get a graphical choice of boot devices.
Boot from the CD and run Disk Utility to Repair Permissions. That may fix the Finder crashing, assuming it was hitting a file it required, but didn't have permission to access.
If that doesn't fix it, I've seen that effect when a corrupted bundle was on the Desktop. You can test that by logging in as another user (create another user account if need be) and see if the Finder is stable there.