21650 PHP/js/XML/SQL Script Error

I have a script build in PHP/SQL/Flash/Javascript and it works great on my server but when I move it to another server and try to use it, I get the following error. “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 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 Error Document to handle the request.” I'm not sure what is happening here and need some help fixing. It seems as though there is something different with the new server I'm trying to install on because I can install the script fine on multiple hosting accounts and domain within my own server but not on this new one. The script takes about 5 minutes to install. I'd need you to try installing the script on both servers to see the different results then fix this issue. I will provide an installation instructions doc explaining how to set up the script. Thanks!