WordPress 500 Error on a Default Windows Plesk Install

Database Creation
WordPress is powered by a mySQL database, so if any issues arise when you create or configure the database, an internal server error may occur. The first step is to make sure that Plesk creates the database. If you are not using a one-click installation method for WordPress in Plesk, you can create a database manually. You'll need to enter the database information into the 'wp-config.php' file in the WordPress directory. If you enter this information incorrectly, a 500 internal server error may be generated.
Htaccess
WordPress uses .htaccess files to control the appearance of permalinks. Without a configured .htaccess file, WordPress shows the base URLs, which are comprised of numbers designating each blog post and page. Correct parameters need to be added to the .htaccess file to display the permalinks with the names of the blog posts. If your .htaccess file is not configured properly, it may block access to internal pages on your site. You can edit the .htaccess file through Plesk's file manager or an FTP program.
Missing Files
If your Internet connection dropped while you were uploading files to your server, some of your WordPress files may be corrupt or missing. If you are manually installing WordPress via Plesk and you lose connectivity while uploading, delete the WordPress setup files from the server and upload them again to make sure that all of the required files are copied successfully.
Considerations
Your Web server itself needs to be configured to support a WordPress installation. If Plesk offers a one-click WordPress installation option, chances are this process will be handled automatically. However, if you are still encountering the 500 error, it's worth checking the server setup. If you don't have access to your server's operating system, you may need to ask your Web host to check this for you. The current version of WordPress needs a server with PHP 5.2.4 at a minimum, as well as mySQL 5.0. Additional recommendations include Apache or Nginx, though neither program is required.