I install Leopard on my MacBook Pro on Friday evening, messed around with it a little, and then put the computer to sleep until Saturday. On Saturday, I had reason to restart, and that’s when I saw it: upon restart, I would get the gray Apple logo, then a spinner beneath that logo, then eventually (3 minutes?) a circle-with-a-slash-through-it where the Apple logo was.
Nuts.
I tried several things to no avail, including verifying the disk and repairing disk permissions. I even reinstalled Leopard which actually brought the computer up again but still didn’t solve the problem upon restart.
I just now got off the phone with Apple — 47 minutes from dialing to finished with about a 10-15 minute wait before I spoke to a human. Following his instructions, I booted the computer into “safe mode” (by holding down the Shift key after restart). Then I deleted all my login items (via System Preferences –> Accounts). However, the clincher (I believe) was deleting all the folders in /Library/StartupItems which included, among other things, an old Nortel Contivity VPN client.
All better now!