Its your host as far as i can tell, email them and ask them to take a look again. If they refuse, move on to a different host and tell them so.
OR,
Do you use cpanel? Try deleting the account for each URL and recreating it and reloading the pages.
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator,
admin@server4.web-mania.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.
Apache/1.3.27 Server at www.party-bingo-bonus-code.com Port 80