I just upgraded to the latest security update of 10.8 last night, told it not to reboot (clicked "later"). After declining to reboot, immediately shut down (not rebooted) Macbook Pro for the night and went to sleep.
This morning, I turned the computer on. After logging in, I have a couple minutes (or less) and then the computer irretrievably freezes. I tried multiple times, same deal. Booted up without loading the previous windows. Still freeze. Stopped all auto-start programs, still freeze.
Repaired disk and partition. Plenty of time, no freeze in the recovery mode.
However, after logging back into my regular account, the freeze issue persisted.
Logged into my wife's account - no freeze issue. OK, so maybe just my account. So I went to System Preferences, hit the unlock button and escalated privileges with my main user/pass and created a new account. However, maybe 30 seconds later, the computer froze irretrievably again. Mouse and keyboard do not respond. Typical animations on the screen have frozen, so it's not just the input devices.
Forced a power off and then booted into the brand new account. Thirty minutes in, still no freeze! This is great, except I had the other account all the way I wanted to and would rather just figure out and fix whatever's freezing up.
How might I do this? I can't find reports of mass problems with the latest security update online. I'm guessing it's a confluence of something in my config plus the latest update. How should I go about diagnosing?
For right now, going to Apple Store is not going to happen (for a variety of reasons, chief among them time, distance, and general daintiness of my poor old and decrepit laptop!).
Try booting into the Safe Mode using your normal account. Disconnect all peripherals except those needed for the test. Shut down the computer and then power it back up. Immediately after hearing the startup chime, hold down the shift key and continue to hold it until the gray Apple icon and a progress bar appear. The boot up is significantly slower than normal. This will reset some caches, forces a directory check, and disables all startup and login items, among other things. When you reboot normally, the initial reboot may be slower than normal. If the system operates normally, there may be 3rd party applications which are causing a problem. Try deleting/disabling the third party applications after a restart by using the application uninstaller. For each disable/delete, you will need to restart if you don't do them all at once.