If when starting tomcat in ubuntu get the following error

INFO: Loaded APR based Apache Tomcat Native library 1.1.19.
Apr 3, 2012 19:14:12 AM org.apache.catalina.core.AprLifecycleListener init
INFO: APR capabilities: IPv6 [true], sendfile [true], accept filters [false], random [true].
Apr 3, 2012 19:14:12 AM org.apache.coyote.http11.Http11AprProtocol init
SEVERE: Error initializing endpoint
java.lang.Exception: Socket bind failed: [22] Invalid argument
at org.apache.tomcat.util.net.AprEndpoint.init(AprEndpoint.java:612)
at org.apache.coyote.http11.Http11AprProtocol.init(Http11AprProtocol.java:107)
at org.apache.catalina.connector.Connector.initialize(Connector.java:1058)
at org.apache.catalina.core.StandardService.initialize(StandardService.java:677)
at org.apache.catalina.core.StandardServer.initialize(StandardServer.java:795)

then probably you have to disable IPV6 in your machine. Visit this link to see how