Massive AU failure

Last evening Logic refused to launch. (Has worked flawlessly since setting up new iMac quad-core around Christmas.) Trashing preferences did nothing. A call to Apple suggested reinstalling the Logic app, leaving all other content on external drives. Logic then launched as expected. However, every AU failed validation--including Apple's own! I use very few 3rd party AUs (EZDrummer, Ozone, Garritan Personal Orch, and PodFarm), and all of these worked prior to the reinstall. But for Apple's own to fail--????

A second call to Apple led to the dreaded "reinstall the system." I'd sure rather avoid that nightmare if I can. Anyone have any other ideas? Obviously something deep is up given that an Apple app doesn't approve of its own components.

Jim