Have you installed internet explorer SP1? It comes with a updated outlook express which should fix the problems your having.
http://www.microsoft.com/downloads/results.aspx?productID=&freetext=outlook+express&DisplayLang=en
Also, you have to go into tools / accounts / double click on your account / choose the advanced tab / check the "leave a copy of message on server" if you don't want to delete them off the server.
http://www.microsoft.com/downloads/results.aspx?productID=&freetext=outlook+express&DisplayLang=en
Also, you have to go into tools / accounts / double click on your account / choose the advanced tab / check the "leave a copy of message on server" if you don't want to delete them off the server.