Buzz Commments displays comments from your Google Buzz stream to your WordPress posts, directly in the comment list on your blog.
You've to configure your Supercache that it invalidates the cache periodical. The use of Supercache will increase the time until the new comments are displayed at your posts.
Install the newest Pluginversion. If you still get the error open a ticket with at least the WordPress version and other plugins you use as information.
Please open a ticket! Provide at least WordPress version, plugin version and your Google Buzz Profile URL as information.