Some problems when install drupal 6 in a subdomain

After install drupal 6 as subdomain at my webserver, I got a message "Internal Server 500 Error"

What I did is to edit .htaccess. Just comment on the following line

# Follow symbolic links in this directory.
#Options +FollowSymLinks

Also .htaccess under files directory (mine: /public_html/drupal/sites/default/files
comment on the following two lines.
#Options None
#Options +FollowSymLinks