Well, I went back to Hostgator and got a different support person. Apparently the problem was that there was no .htaccess file. Once this was added with the following contents, it worked perfectly.
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress
