Is it there with different browsers? We’re aware of the issues being caused by the current multi site install and we will be working on moving away from this to a single site install. This should cure a lot (hopefully all) of the cookie issues we’ve been having.
Are you 100% certain you have viewed all messages? In your message list at the top right corner there is a paging indicator. If more than one page exists, make sure you have read all of the messages on page 2, 3 ect.