MAMP/Boutique Quickstart Installation Issue

I have been trying to set up a localhost on my MAC machine. After running into many permission/ownership problems with XAMPP, I switched to MAMP. I successfully installed the Boutique quickstart installation file. I can access the Joomla back-end and install extensions, etc, but I get the following error when I try to access the actual site:

Server error
The website encountered an error while retrieving http://localhost:8888/boutiquesite/. It may be down for maintenance or configured incorrectly.
Here are some suggestions:
Reload this webpage later.
HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.

Does anyone have an idea of what is going on? BTW, when I install the basic Joomla 1.7, it works perfectly.

Thanks in advance for any help!

Probably you have still problem with permissions or with htaccess, please also check your server error log, maybe there you find more informations.