I got the same error on Windows 7 64-Bit using JBoss 4.0.4.
Using the command "netstat -ao" I noticed that port 8080 is occupied by process 4 (System).
Thus I changed the connector port to 8081 (JBoss\server\default\deploy\jbossweb-tomcat55.sar\server.xml) and JBoss works again.