I too am getting a blank page when I click on the sitemap module which has been activated for All Visitors.
When I click on the following link
http://www.orchardcounty.com/modules.php?name=Sitemap&op=Google
I get the following:
<?xml version="1.0" encoding="UTF-8" ?>
- <urlset xmlns="http://www.google.com/schemas/sitemap/0.84" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.google.com/schemas/sitemap/0.84
http://www.google.com/schemas/sitemap/0.84/sitemap.xsd">
- <!-- Created by nukeSEO Sitemap 1.0B
-->
- <!-- Updated on 2007-05-11T20:05:59+0100
-->
</urlset>
BTW I'm using MySQL 3.23 Phpnuke 7.6 3.2 patched.
I have searched through the forums to no avail. Apologies if I have missed something.