diff --git a/src/java/org/apache/lucene/index/FieldsReader.java b/src/java/org/apache/lucene/index/FieldsReader.java
index c3efe455bb7..ecb9f2986a2 100644
--- a/src/java/org/apache/lucene/index/FieldsReader.java
+++ b/src/java/org/apache/lucene/index/FieldsReader.java
@@ -159,7 +159,9 @@ final class FieldsReader {
       }
       catch (DataFormatException e) {
         // this will happen if the field is not compressed
-        throw new IOException ("field data are in wrong format: " + e.toString());
+        IOException newException = new IOException("field data are in wrong format: " + e.toString());
+        newException.initCause(e);
+        throw newException;
       }
     }
   
diff --git a/src/java/org/apache/lucene/index/SegmentMerger.java b/src/java/org/apache/lucene/index/SegmentMerger.java
index 534b857d699..d4fd203db69 100644
--- a/src/java/org/apache/lucene/index/SegmentMerger.java
+++ b/src/java/org/apache/lucene/index/SegmentMerger.java
@@ -332,7 +332,8 @@ final class SegmentMerger {
         doc += base;                              // convert to merged space
 
         if (doc < lastDoc)
-          throw new IllegalStateException("docs out of order");
+          throw new IllegalStateException("docs out of order (" + doc +
+              " < " + lastDoc + " )");
 
         df++;
 
diff --git a/src/java/org/apache/lucene/index/SegmentReader.java b/src/java/org/apache/lucene/index/SegmentReader.java
index 4ed421a03c3..520e4a6bab3 100644
--- a/src/java/org/apache/lucene/index/SegmentReader.java
+++ b/src/java/org/apache/lucene/index/SegmentReader.java
@@ -94,12 +94,12 @@ class SegmentReader extends IndexReader {
                            SegmentReader.class.getName());
       IMPL = Class.forName(name);
     } catch (ClassNotFoundException e) {
-      throw new RuntimeException("cannot load SegmentReader class: " + e);
+      throw new RuntimeException("cannot load SegmentReader class: " + e, e);
     } catch (SecurityException se) {
       try {
         IMPL = Class.forName(SegmentReader.class.getName());
       } catch (ClassNotFoundException e) {
-        throw new RuntimeException("cannot load default SegmentReader class: " + e);
+        throw new RuntimeException("cannot load default SegmentReader class: " + e, e);
       }
     }
   }
@@ -123,7 +123,7 @@ class SegmentReader extends IndexReader {
     try {
       instance = (SegmentReader)IMPL.newInstance();
     } catch (Exception e) {
-      throw new RuntimeException("cannot load SegmentReader class: " + e);
+      throw new RuntimeException("cannot load SegmentReader class: " + e, e);
     }
     instance.init(dir, sis, closeDir, ownDir);
     instance.initialize(si);
diff --git a/src/java/org/apache/lucene/index/TermInfosWriter.java b/src/java/org/apache/lucene/index/TermInfosWriter.java
index 5e78487a939..4dc138bb0de 100644
--- a/src/java/org/apache/lucene/index/TermInfosWriter.java
+++ b/src/java/org/apache/lucene/index/TermInfosWriter.java
@@ -92,11 +92,14 @@ final class TermInfosWriter {
   final void add(Term term, TermInfo ti)
        throws IOException {
     if (!isIndex && term.compareTo(lastTerm) <= 0)
-      throw new IOException("term out of order");
+      throw new IOException("term out of order (\"" + term + 
+          "\".compareTo(\"" + lastTerm + "\") <= 0)");
     if (ti.freqPointer < lastTi.freqPointer)
-      throw new IOException("freqPointer out of order");
+      throw new IOException("freqPointer out of order (" + ti.freqPointer +
+          " < " + lastTi.freqPointer + ")");
     if (ti.proxPointer < lastTi.proxPointer)
-      throw new IOException("proxPointer out of order");
+      throw new IOException("proxPointer out of order (" + ti.proxPointer + 
+          " < " + lastTi.proxPointer + ")");
 
     if (!isIndex && size % indexInterval == 0)
       other.add(lastTerm, lastTi);                      // add an index term