Final Edit-
Temporary workaround: click iOS Simulator > Reset Content and Settings... and run again.
This error message may reappear at random. For me, it happens when I launch a different application. There are several threads in Apple dev forums and in StackOverflow about this problem, but none have a definitive answer. This seems to be a SDK error to be fixed in the next Xcode version.
Updated: October 3.
CREDIT - Please check this answer - Xcode 5 Error CertUIFramework.axbundle
Further Edit
Although this was potentially the issue resolution at the time. I believe some of the newer answers below relating to the better touch tool are in fact the correct resolutions.