Script compilation error - on intel iMac

I have freshly installed and run the Unity trial version and I get the following message on the bottom of the unity window:

“Script compilation error: Couldn’t replace Library/ScriptAssemblies/Assembly - UnityScript - first pass.dll”

The same happens if I create a new project. What’s wrong?

Thanks.

Unity 1.2.1 does not work on intel imacs.
We will support universal binary in unity with version 1.2.3.

Try the 1.2.2 beta; it behaves much better on the Intel Mac.