I was writing a simple program that uses Levenstein's algorithm to find the 
distance between two strings. Here's the code (just the first part of it):
 

//compare two strings and return the distance between them
package string_processing;

import java.io.*;

public class StringDistance {
    public static void main(String args[]) {
 String f, s;
 System.out.print("Enter first string: ");
 BufferedReader br = new BufferedReader(new InputStreamReader( System.in));
 s = br.
    }
}

and you know why there's nothing after " ... br." - the autocompletion list 
didn't popup .. and there was an exception (red Stop sign in the bottom right 
corner of the window). Here are the details:

javax.jmi.reflect.InvalidObjectException: Object with MOFID 76F46923-2007-11DB-
B748-1386476AAA77:0000000000000FEB no longer exists, class: org.netbeans.jmi.
javamodel.JavaModelPackage$Impl
 at org.netbeans.mdr.handlers.BaseObjectHandler._getDelegate (BaseObjectHandler.
java:359)
 at org.netbeans.mdr.handlers.PackageProxyHandler.
getPackageDelegate(PackageProxyHandler.java:71)
 at org.netbeans.mdr.handlers.PackageProxyHandler.
_handleGetClassProxy(PackageProxyHandler.java :102)
 at org.netbeans.jmi.javamodel.JavaModelPackage$Impl.getArray(Unknown Source)
 at org.netbeans.modules.javacore.jmiimpl.javamodel.MetadataElement.
resolveType(MetadataElement.java:1574)
 at org.netbeans.modules.javacore.jmiimpl.javamodel.ParameterImpl.getType 
(ParameterImpl.java:102)
 at org.netbeans.jmi.javamodel.Parameter$Impl.getType(Unknown Source)
 at org.netbeans.modules.editor.java.NbJMIResultItem$CallableFeatureResultItem.
<init>(NbJMIResultItem.java:433)
 at org.netbeans.modules.editor.java.NbJMIResultItem$MethodResultItem.
<init>(NbJMIResultItem.java:341)
 at org.netbeans.modules.editor.java.
NbJavaJMICompletionQuery$DefaultJMIItemFactory.
createMethodResultItem(NbJavaJMICompletionQuery.java :1411)
 at org.netbeans.modules.editor.java.
NbJavaJMICompletionQuery$DefaultJMIItemFactory.
createResultItem(NbJavaJMICompletionQuery.java:1431)
 at org.netbeans.modules.editor.java.JMIUtils.findFeatures(JMIUtils.java :860)
 at org.netbeans.modules.editor.java.JMIUtils.findFeatures(JMIUtils.java:399)
 at org.netbeans.modules.editor.java.NbJavaJMICompletionQuery$Context.
findFieldsMethodsAndInnerClasses(NbJavaJMICompletionQuery.java :1057)
 at org.netbeans.modules.editor.java.NbJavaJMICompletionQuery$Context.
resolveExp(NbJavaJMICompletionQuery.java:285)
 at org.netbeans.modules.editor.java.NbJavaJMICompletionQuery.
getResult(NbJavaJMICompletionQuery.java :57)
 at org.netbeans.editor.ext.java.JavaCompletionQuery.query(JavaCompletionQuery.
java:139)
 at org.netbeans.editor.ext.java.JavaCompletionQuery.query(JavaCompletionQuery.
java:74)
 at org.netbeans.modules.editor.java.JavaCompletionProvider$Query.query 
(JavaCompletionProvider.java:108)
 at org.netbeans.spi.editor.completion.support.AsyncCompletionTask.
run(AsyncCompletionTask.java:189)
 at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:493)
[catch] at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.
java:926)