I used the pre-configured Tomcat version 4.1.29.
Standalone, it works well when I type http://localhost/

However,
1) When I start sever from Sun Java Studio,

Error msg: During Tomcat server execution/debugging/deployment process

The web application cannot be deployed or executed because the server shutdown port 8005 on host localhost is in use.
To use a different port for the server shutdown, expand the server registry in the runtime tab and navigate to the tomcat installation node. Open the nodes property sheets and type a different server shut down port number for the server port property.

And it changes the localhost to 8083. Why?

2) though it previously works, now also fails to work.. http://localhost/ results:

HTTP Status 404 - /

type Status report
message /
description The requested resource (/) is not available.

Apache Tomcat/4.1.29