Command /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/clang failed with exit code 1
Warnings:
"iOS deployment target '5.0' for architecture 'armv6' and variant 'normal' is greater than the maximum value '4.2.99' for the iOS 4.2 SDK.
"
"ld: warning: unexpected srelocation type 9"
You have configured your project to deploy to iOS 5.0 but you are building against iOS 4.2 SDK.
Generally you do this the other way around: build against the latest SDK (say, 5.0) but set the deployment for the lowest version possible that you support (say, 4.2).