Hi there umma08, if you believe the issue to be caused by the 10.7.4 updatem I would recommend calling Apple and informing them that only machines running 10.7.4 are effected.
They may be able to resolve the issue, or at least isolate the problem to either the 10.7.4 update or something else, like another application that you have that could be having an issue working with 10.7.4.
Try starting the computer holding the "Shift" key to put the Operating System in Safe Mode:
http://support.apple.com/kb/HT1455
If it works fine in Safe Mode: Then the issue may be caused by a Non-Apple application that you have installed on these machines. In which case you would want to start checking for updates for all your Non-Apple software.
If the issue persists in Safe Mode, definately call Apple if you believe the issue to have been caused by the 10.7.4 Update. You can contact Apple Care at (800) 275-2273. Inform the Tech Advisor that you only have the issue on computers that have installed. If it is an Apple Issue, they will only know about it once someone calls in and reports it.
P.S. Always have a backup: This can protect against software issue, you accidentally deleting something important or a Hard Disk failure.