This is a new iPhone project, only 1 target (different from this question)
On build we get:
Failed to launch simulated application: Unknown error.
>
I can confirm that a naming conflict was the source of our problem. We had a filesystem folder named resources
inside the Xcode group named Resources
. Sometimes we would get the error and a system would lock up and sometimes it would not. Changing the folder to the name assets
resolved our problem. After reading some of the above comments - it appears that Xcode group names can clash with directory/folder names.