all in one seo pack wordpress?

I am on Wordpress version 2.5. I’ve installed version All in One SEO Pack. When I activate the plugin and visit my blog, I receive the following error: "Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request." my url is http://wanita.cheatgame.info please help me, thanks

Public Comments

1. Go under settings/permalinks and click the save changes button and see if that helps.
2. Have you followed the install functions step by step? As the previous answerer states, your permalink structure may need to be updated to activate the URL rewrite.