How do I resolve the java error while accessing Atrium Core?

successfully installed ARS and Atrium Core 7.5 on Windows 2003 virtual box with SQL 2005.
Customer can access mid-tier and AR System Administration Console without any issue. But when they click on the Atrium Core Console Link, it throws the following java error.

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: Servlet execution threw an exception


root cause

java.lang.NoClassDefFoundError: com/bmc/atrium/lcds/FlexAtriumContext
java.lang.Class.getDeclaredConstructors0(Native Method)
java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
java.lang.Class.getConstructor0(Unknown Source)
java.lang.Class.newInstance0(Unknown Source)
java.lang.Class.newInstance(Unknown Source)
com.remedy.arsys.plugincontainer.impl.PluginFactory$PluginInfo.getPlugin(Unknown Source)
com.remedy.arsys.plugincontainer.impl.PluginFactory.getInstance(Unknown Source)
com.remedy.arsys.plugincontainer.impl.PluginContextImpl.(Unknown Source)
com.remedy.arsys.plugincontainer.impl.PluginContainer.setupEnv(Unknown Source)
com.remedy.arsys.plugincontainer.impl.PluginContainer.processRequestInfo(Unknown Source)
com.remedy.arsys.stubs.AuthenticationHelperServlet.doRequest(Unknown Source)
com.remedy.arsys.stubs.GoatHttpServlet.postInternal(Unknown Source)
com.remedy.arsys.stubs.GoatHttpServlet.doGet(Unknown Source)
javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

note The full stack trace of the root cause is available in the Apache Tomcat/5.5.25 logs.

Product
BMC Atrium CMDB Enterprise Manager (version 7.5.00)

Environment
DR: BMC Atrium Core;

Solution
The stdout log shows:

INFO: Server startup in 48875 ms
- Connects to ARServer bmc-itsm75 through com.bmc.arsys.api.ProxyJRpc@1a3b359
- Created proxy 1 by Tid_37 for server bmc-itsm75
- Servlet.service() for servlet PluginServlet threw exceptionjava.lang.NoClassDefFoundError: com/bmc/atrium/lcds/FlexAtriumContext

at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
at java.lang.Class.getConstructor0(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at com.remedy.arsys.plugincontainer.impl.PluginFactory$PluginInfo.getPlugin(Unknown Source)
at com.remedy.arsys.plugincontainer.impl.PluginFactory.getInstance(Unknown Source)
at com.remedy.arsys.plugincontainer.impl.PluginContextImpl.<init>(Unknown Source)
at com.remedy.arsys.plugincontainer.impl.PluginContainer.setupEnv(Unknown Source)
at com.remedy.arsys.plugincontainer.impl.PluginContainer.processRequestInfo(Unknown Source)
at com.remedy.arsys.stubs.AuthenticationHelperServlet.doRequest(Unknown Source)
at com.remedy.arsys.stubs.GoatHttpServlet.postInternal(Unknown Source)
at com.remedy.arsys.stubs.GoatHttpServlet.doGet(Unknown Source)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Unknown Source)
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First verified that the BMC Software\BMC Atrium Core\<server_name>\cmdb\plugins is referenced in the Path environment variable.
Restartging tomcat or Mid-tier server didn't resolve the issue.

The mid-tier log reported the following error:

Feb 9, 2009 11:00:41 AM - SEVERE (com.remedy.log) : BMC Remedy Mid Tier version 7.5.00 Build 200812291922
Feb 9, 2009 11:02:53 AM - WARNING (com.remedy.log.SERVLET) : ARERR [90] Cannot establish a network connection to the AR System server : ONC/RPC program not registered bmc-itsm75

After restarting the windows box with AR Server, the issue got resolved.