Login issue when using a dashboard on the base URL

I have a dashboard set to the base URL of my PU server. This dashboard acts as a landing page to give access to various other dashboards the user has access to use. When the user goes to the base url they log in and the landing page appears as expected. If the user uses the “Sign Out” feature in the top right they log off and go to a page that shows a login button. If they use that login button and login again they get “access denied” This is because that button appends ?returnUrl=/admin to the base url. This causes user confusion because even if they click “Log Out” on the error message page it always tries to access the admin page which they do not have access to. Is this a configuration issue somewhere? I am running 4.0.5