Unable to lookup RMI object

We recently experienced unable to login to process flow administrator, LBI failed to come up and MSCM failed to upload to back office. We found error in back office SystemOut log as below:

We ended up to restart app server to solve the issue. Anyone has any idea what was the root cause?

[5/5/10 13:53:20:144 CDT] 00000ad0 ServletWrappe E SRVE0068E: Uncaught exception thrown in one of the service methods of the servlet: daservlet. Exception thrown : javax.servlet.ServletException: Error: Unable to lookup RMI object rmi://blawson1.bhcs.pvt:17003/dbSecurity
at com.lawson.bpm.webcomponents.RmiBaseServlet.lookupRmiServerObject(Unknown Source)
at com.lawson.bpm.db.model.impl.daservlet.servlet.DAServlet.doPost(Unknown Source)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:989)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:930)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:145)
at com.lawson.bpm.webcomponents.BpmSSOServletFilter.doFilter(Unknown Source)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:87)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:766)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:674)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:498)
at com.ibm.ws.wswebcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:464)
at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:90)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:744)
at com.ibm.ws.wswebcontainer.WebContainer.handleRequest(WebContainer.java:1455)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:113)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:454)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:383)
at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:102)
at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:136)
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:195)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:743)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:873)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1469)