Please re-download and install the 10.7.3 update. You can locate it at 10.7.3 (Client Combo). Follow the on-screen instructions. Then test it out, if you still have the same problem please restart, when you hear the startup tone hold down the Option Key and then choose the Recovery Partition. Then open Disk Utilities and Repair Disk Permissions 2x. Then exit DU, restart normally and re-test.