Kosmo:
I am getting the same error. My password for my server is not the same as my hosting account that has my Fantastico CP installed in it. Below is the error I am getting on almost any new install. Can you help?
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator,
webmaster@thunderhosting.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.