updated membership pro and now site has crashed

I updated Membership Pro this morning and the site worked for an hour or so then crashed, there is a script: 500: Internal server error

This error is generated when a script running on the server could not be implemented or permissions are incorrectly assigned for files or directories

Troubleshooting suggestions:

Temporarily disable any rewrite rules by renaming your .htaccess file if it exists.

Ensure that any CGI or Perl scripts have at least .755. permissions.

If trying to run PHP and you get this error, you may have an invalid php.ini in your /cgi-bin, or may be missing your php.dat file in this folder.