Assuming there was an issue with my system I moved all the files I wanted to keep to /Users/Shared and deleted everything else on my disk (using Terminal). I reinstalled Lion and added 6 Apple Developer certificates to my keychain. As before SystemCACertificates refuse to stay in the System keychain list (Keychain Access->Keychain List->add...) I installed the Apple Developer Certificates so the package would be trusted but when I try to install SmartCard Services Update 2.0b2 I get "The installation failed. The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance." The installer logs say "Feb 21 16:07:33 ... installd[921]: PackageKit: Install Failed: Error Domain=PKInstallErrorDomain Code=102 "The package “Smart Card Services Update 2.0b2-Lion-signed” is untrusted." UserInfo=0x7fc441e080e0 {NSLocalizedDescription=The package “Smart Card Services Update 2.0b2-Lion-signed” is untrusted., NSURL=file://localhost/Users/.../Downloads/Smart%20Card%20Services%20Update%202.0b2-Lion-signed.pkg#cac.pkg, PKInstallPackageIdentifier=org.macosforge.SmartCardServices.cac.pkg, NSUnderlyingError=0x7fc441e06610 "The operation couldn’t be completed. CSSMERR_TP_NOT_TRUSTED"} { NSLocalizedDescription = "The package \U201cSmart Card Services Update 2.0b2-Lion-signed\U201d is untrusted."; NSURL = "file://localhost/Users/.../Downloads/Smart%20Card%20Services%20Update%202.0b2-Lion-signed.pkg#cac.pkg"; NSUnderlyingError = "Error Domain=NSOSStatusErrorDomain Code=-2147409622 \"The operation couldn\U2019t be completed. CSSMERR_TP_NOT_TRUSTED\" UserInfo=0x7fc441e05660 {SecTrustResult=5, PKTrustLevel=PKTrustLevelNotTrusted, NSLocalizedFailureReason=CSSMERR_TP_NOT_TRUSTED}"; PKInstallPackageIdentifier = "org.macosforge.SmartCardServices.cac.pkg"; } It's going to take a long time for me to move all my files off this disk so I can reformat and I'm betting I'll see the same error. Files sitting in /Users/Shared should have no effect on the installation of OS X.