Xcode 4 failure to symbolicate Crash Log

I have just updated my Xcode to X.Y.Z. Now I have a problem with the symbolication of the crash logs received from my tester and even from my phone too.

When I build the AdHoc distribution I am using the "Arhive" scheme, then I create the *.ipa file singing it with my developer credentials.

Is this the issue? And I can't find the dSym files for these AdHoc builds.

Further to coob's answer, I find adding these directories to Spotlight's ignore list (System Preferences → Spotlight → Privacy) helps:

• ~/Library/Developer/Xcode/DerivedData/ (Xcode 4 build artefacts)
• ~/Library/Application Support/iPhone Simulator/ (file system for the iPhone Simulator)

Like this:

(See this blog post for additional detail.)

Update: from a comment by joerick: "This works, but it also meant that Instruments.app couldn't find the debug symbols, so I had to remove DerivedData from the Privacy list to do some profiling." - bear this in mind if you use Instruments.