Problem when opening a database from the web

We have a web page that has links to several notes discussion databases. When we first set them up you could click on the link and the discussion database would open in a new browser window (target=_new). The next morning when we tried the link and got “Page not found”. Then I went into the notes client, opened the database, closed the client, and then the link worked again. This is happening every morning. We have 2 servers that are clustered. The web site db and all of the discussion databases are replicated on both servers.

Thanks in advance.