Error starting Jboos 7.1 Address already in use: JVM_Bind /0.0.0.0:80

I'm trying to start my Jboss 7.1 server with a new application, but the error is occurring:

[org.apache.coyote.http11.Http11Protocol] (MSC service thread 1-1) Error initializing endpoint: java.net.BindException: Address already in use: JVM_Bind /0.0.0.0:80
    at org.apache.tomcat.util.net.JIoEndpoint.init(JIoEndpoint.java:983) [jbossweb-7.0.13.Final.jar:]
    at org.apache.coyote.http11.Http11Protocol.init(Http11Protocol.java:190) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.connector.Connector.init(Connector.java:983) [jbossweb-7.0.13.Final.jar:]
    at org.jboss.as.web.WebConnectorService.start(WebConnectorService.java:267) [jboss-as-web-7.1.1.Final.jar:7.1.1.Final]
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.2.GA.jar:1.0.2.GA]
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746) [jboss-msc-1.0.2.GA.jar:1.0.2.GA]
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) [rt.jar:1.6.0_39]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) [rt.jar:1.6.0_39]
    at java.lang.Thread.run(Thread.java:662) [rt.jar:1.6.0_39]

Usually (at least with me) this is due to conflicts with the ports used by Skype, which I have already changed.

I accessed the command prompt by running the command netstat -aob to check which program is using that port, and tells me that it is the system, and could not get ownership information.

Has anyone ever had this problem and could you help me?