Checkout Error and Admin TOOLs ERROR

[Guest]

Hi can someone help me and tell why I'm getting this error when I try to check out my Items (The requested URL /oscommerce/catalog/checkout_shipping.php was not found on this server.)

 

And also in the admin page when I click on TOOLS I get this ERROR>(The server encountered an internal error or misconfiguration and was unable to complete your request.

 

Please contact the server administrator, [email protected] 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.) :'(