Q: can't do normal boot up since 10.8.3 update

This was my feedback to Apple -

After installing 10.8.3 update my iMac 27" Late 2009 no longer boots up. The OS will however boot up in safe mode.

Formated the hard drive and reinstalled Mac OS Lion and the OS booted up correctly however once again after installing 10.8.3 update the computer would no longer boot properly.

I am hoping you will resolve this glitch for the next OS update.

Do a backup, using either Time Machine or a cloning program, to ensure files/data can be recovered. Two backups are better than one.

Try a restart.

Run Disk Utility/Repair Permissions. Run until it reports no errors. If there is a recurring error, see the article on what permission errors can be ignored.

Disk Utility                                                       

Disk Utility Repair Permissions You Can Safely Ignore

Try setting up another admin user account to see if the same problem continues. If Back-to-My Mac is selected in System Preferences, the Guest account will not work. The intent is to see if it is specific to one account or a system wide problem. This account can be deleted later.

Isolating an issue by using another user account

If the problem is still there, try booting into the Safe Mode.  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. 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. For each disable/delete, you will need to restart if you don't do them all at once.

Safe Mode

Safe Mode - About

Restart the computer holding down the command - option/alt - P - R keys before the grey screen appears. Continue to hold until you hear the startup chime for the second time.

Reset NVRAM/PRAM

Try an SMC reset. The article covers when this is required, but doing this will not affect anything.

Reset SMC

General information.

Isolating issues in Mac OS X

Troubleshooting Permission Issues

Step by Step to Fix Your Mac

Thanks for the suggestions however there is a bug in this update OS X 10.8.3 for specific computers.

I will reinstall the OS X tonight and just stay at 10.8.2 until Apple resolves this issue.