Description: This is often encountered when you try to start your server (WAS). It is typically seen with RAD6.0. I never came across the problem with RAD 7.0.
Reason: Occurs when the server process related to a particular server instance is not terminated and you try to start the same server. So the applications running on the ports give a problem because the port is already occupied.
Solution: Go to task manager, and end the process in the name java.exe.
WARNING: If you have multiple servers running, you might risk ending some other server process.