Also entered as FogBugz case. The repro' steps are, 1. Launch 5.0.0b14 installer. 2. Click through to point at which the downloads start for your selected components. 3. Go away and make a cup of coffee. [time passes] Result is that given enough time the 2nd prompt for authentication (on Mac OS X) will timeout, at least I presume it was a timeout, and leave you with this panel prompt. I think it'd be useful for those folks who leave the keyboard for an extended period of time while the download happens if at the end prior to showing the auth prompt either, a) Show a 'Ready to install, click to Continue' panel prior to the system authentication prompt to install the PKG, or, b) Provide a Retry button on the authentication error alongside Quit. As it stands you are forced to quit the installer and re-start/download.