Internal Server Error 500 when Accessing Multisite Dashboard

I just installed Multisite for the first time! I installed it on a sub-domain of a website and set up via the sub-directory method and added a new site, but now get an error message when I try to log in to the new site's dashboard. Can you help? Here's the error message I get:

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator and inform them of the time the error occurred, and the actions you performed just before this error.

More information about this error may be available in the server error log.

Apache Server at Port 80

Oh, my host is GoDaddy, if that helps with anything...