beta 4 - successful installation - unable to log into manager

Hello guys
just successfully installed beta 4 - I’m still unable to log into the manager:

Safari can’t open the page “http://localhost/cms/modxRev/manager/” because the server unexpectedly dropped the connection. This sometimes occurs when the server is busy. Wait for a few minutes, and then try again.

I really hope we can get this fixed so I can start testing.

Thank you in advance for your help.
OS X 10.6.1, MAMP 1.8.3