Cannot run Websphere 5.1 or 5.1.1 Express [Fix]

This was submitted by Jürgen Schwibs

Environemnt: Eclipse 3.1
J2EE Server: WebSphere Server 5.1.0
WepSphere Server 5.1.1 Express

Configured to use the Java Environment under <WAS>\AppServer\Java

Description:
If you try to start the WebSphere server under MyEclipse you will get an javacore exception:

Solution:
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Copy the shared libarry dt_socket.dll into <WAS>\AppServer\Java\bin OR edit the “Paths” preferences under the Webpshere connector settings and append the directory containing this file to the Library Path (last section on that preference page).