codesign failed with exit code 5

Hi everybody,

yesterday I renewed my dev account, at first I had no problem archiving apps to test them into my ipad, but suddenly every build gave me "build failed" with this error:

CodeSign /Users/cristiano/Library/Developer/Xcode/DerivedData/MultiTargets-cagrakrndtxhj jbeeseyceiigrjj/ArchiveIntermediates/MultiTargets/InstallationBuildProductsLoca t ion/Applications/MultiTargets.app

cd "/Users/cristiano/Downloads/Progetti/unity/unity tool/Augmented Reality/qualcomm resources/iOS/qcar-ios-sdk/samples/MultiTargets"

setenv PATH "/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Developer/usr/bin:/u sr/bin:/bin:/usr/sbin:/sbin"

setenv _CODESIGN_ALLOCATE_ /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/codesign_allocate

/usr/bin/codesign -f -s "iPhone Developer: Cristiano Zelli (XXXXXXXXXX)" --resource-rules=/Users/cristiano/Library/Developer/Xcode/DerivedData/MultiTarg ets-cagrakrndtxhjjbeeseyceiigrjj/ArchiveIntermediates/MultiTargets/Installation B uildProductsLocation/Applications/MultiTargets.app/ResourceRules.plist --entitlements /Users/cristiano/Library/Developer/Xcode/DerivedData/MultiTargets-cagrakrndtxhj jbeeseyceiigrjj/ArchiveIntermediates/MultiTargets/IntermediateBuildFilesPath/Mu l tiTargets.build/Release-iphoneos/MultiTargets.build/MultiTargets.xcent /Users/cristiano/Library/Developer/Xcode/DerivedData/MultiTargets-cagrakrndtxhj jbeeseyceiigrjj/ArchiveIntermediates/MultiTargets/InstallationBuildProductsLoca t ion/Applications/MultiTargets.app

dyld: Symbol not found: _kSecCFErrorArchitecture

Referenced from: /usr/bin/codesign

Expected in: /System/Library/Frameworks/Security.framework/Versions/A/Security

in /usr/bin/codesign

Command /usr/bin/codesign failed with exit code 5

I think that the /System/Library/Frameworks/Security.framework/Versions/A/Security file is corrupted, but I cannot figure it out how to restore it.. I tried to search all over the web for a solution, but I haven't found anything yet.

I'm on a MacPro 4.1, snow leopard 10.6.8, xcode 4.2 with iOS 5.1 platform included, ipad 2 with ios 5.1

I've already tried to revoke my developer and distribution account and creating new ones;

I tried to completely remove xcode and reinstall first xcode 4.0 with ios sdk 4.3 and then 4.2;

I tried to download and open MacOSXUpdCombo10.6.8 with pacifist to reinstall Security.framework

... still I'm getting the same error with all my projects!

Most of my projects are created with Unity, I'm not a programmer, but also when I create a completely new project from Xcode I've always the same error...

Someone who can help me? thank you in advance!