Apache Tomcat/6.0.36This was a guess of my previous post: You are running an Apache Tomcat on the server you've installed XE on. The default port used by your Tomcat is 8080, which is also the default port for the database internal HTTP server that is used to serve the application you are trying to access.
... where you replace +<portnumber>+ with an alternative port, e. g. 8088. You need to change your Link-URL from http://127.0.0.1:8080/apex/f?p=4950 to http://127.0.0.1:8088/apex/f?p=4950 in that case.
exec dbms_xdb.sethttpport(<portnumber>); commit; alter system register;