when people sign up, and you want to view their profile

www.mysite/theadmiralgeek

what is happening is MOD RE_WRITE is changing the links to friendly ones. You can sort this by adding this to the htaccess in your root folder

<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule .+ - [L]
RewriteRule ^([A-Za-z0-9_-]+)$ profile.php?ID=$1 see more [QSA,L]
</IfModule>

or else you can turn off FRIENDLY PERMALINKS IN THE ADMIN PANEL.