Jcrhis, I'm sorry but I don't know and haven't had this problem. I know that when I click on the alerts (my icon in the upper right corner), there aren't anymore after that until there's a fresh alert.
If you're still having this problem, ask your question in the We Are Live thread and eventually a PoodleAdm will see it.
I can assist here to answer this. As Vita said, checking your alerts will dismiss them. Unread Alerts will disappear after 90 days, and read alerts will disappear after 30 days. You can change which items on the forum give you alerts from within your profile settings.