I've identified a problem with XML Google Maps. I am running wp 2.8.
I'm running WP-Spamfree Version 184.108.40.206 and when it is running and I enable XML Google Sitemaps, my plugins page ceases to display the plugings. I have to disable XML Google Sitemaps manually.
I'm not sure where the problem actually is but it could be with WP Spamfree as well. Just thought you should know.