diff --git a/core/org.eclipse.cdt.core.tests/ChangeLog b/core/org.eclipse.cdt.core.tests/ChangeLog
index 4a271be4ba5..74a7371dbbc 100644
--- a/core/org.eclipse.cdt.core.tests/ChangeLog
+++ b/core/org.eclipse.cdt.core.tests/ChangeLog
@@ -5,6 +5,9 @@
 	Moved testErrorHandling_1() from failed tests to CompleteParseASTTest.  
 	Moved testBug44340() from failed tests to CompleteParseASTTest.
 
+2004-02-06 Andrew Niefer
+	Added CompletionParseTest.testBug51260
+
 2004-02-04 John Camelon
 	Added preliminary SelectionParseTests to test SELECTION_PARSE clients. 
 	Added SelectionParseTests to ParserTestSuite.  
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CompletionParseTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CompletionParseTest.java
index 5f10ceddab3..3ab446335a4 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CompletionParseTest.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CompletionParseTest.java
@@ -601,4 +601,42 @@ public class CompletionParseTest extends CompleteParseBaseTest {
 		IASTField field = (IASTField) result.getNodes().next();
 		assertEquals( field.getName(), "aPrivate" );
 	}
+	
+	public void testBug51260() throws Exception{
+		StringWriter writer = new StringWriter();
+		writer.write( " class A { public: void a(); }; " );
+		writer.write( " class B : public virtual A { public: void b(); };" );
+		writer.write( " class C : public virtual A { public: void c(); };" );
+		writer.write( " class D : public B, C { public: void d(); };" );
+		
+		writer.write( " void A::a(){} ");
+		writer.write( " void B::b(){} ");
+		writer.write( " void C::c(){} ");
+		writer.write( " void D::d(){ SP }" );
+		
+		String code = writer.toString();
+		int index = code.indexOf( "SP" );
+		IASTCompletionNode node = parse( code, index );
+		
+		ILookupResult result = node.getCompletionScope().lookup( node.getCompletionPrefix(), 
+		                                                         new IASTNode.LookupKind[]{ IASTNode.LookupKind.THIS },
+																 node.getCompletionContext() );
+		
+		assertEquals( result.getResultsSize(), 4 );
+		
+		Iterator iter = result.getNodes();
+		IASTMethod d = (IASTMethod) iter.next();
+		IASTMethod b = (IASTMethod) iter.next();
+		IASTMethod a = (IASTMethod) iter.next();
+		IASTMethod c = (IASTMethod) iter.next();
+		
+		assertFalse( iter.hasNext() );
+		
+		assertEquals( a.getName(), "a" );
+		assertEquals( b.getName(), "b" );
+		assertEquals( c.getName(), "c" );
+		assertEquals( d.getName(), "d" );
+		
+	}
+	
 }
diff --git a/core/org.eclipse.cdt.core/parser/ChangeLog-parser b/core/org.eclipse.cdt.core/parser/ChangeLog-parser
index 5873078d813..e81b535110c 100644
--- a/core/org.eclipse.cdt.core/parser/ChangeLog-parser
+++ b/core/org.eclipse.cdt.core/parser/ChangeLog-parser
@@ -3,6 +3,10 @@
 	Fixed Bug 44340 - Inline functions fail to resolve references 
 	Fixed Bug 51243 - Content Assist in an empty document causes a NPE 
 
+2004-02-06 Andrew Niefer
+	fixed bug51260 - Content Assist: Completion inside a class method silently fails with a ClassCastException
+	filter symbols without attached AST nodes out of the completion results so the iterator doesn't sometimes return null.
+
 2004-02-04 John Camelon
 	Added preliminary (crude) bSelectionParser IParser implementation for SELECTION_PARSE clients.  
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/ast/complete/ASTNode.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/ast/complete/ASTNode.java
index 7d5d617e336..613729c5bc4 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/ast/complete/ASTNode.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/ast/complete/ASTNode.java
@@ -99,10 +99,14 @@ public class ASTNode implements IASTNode {
 		if(lookupResults == null)
 			return null;
 		
+		//filter out things that are not visible and things that don't have AST nodes attached
 		ListIterator iter = lookupResults.listIterator();
 		while( iter.hasNext() ){
 			ISymbol s = (ISymbol) iter.next();
-			if( !thisContainer.isVisible( s, qualification ) ){
+			if( !thisContainer.isVisible( s, qualification ) ||
+			    s.getASTExtension() == null ||
+				s.getASTExtension().getPrimaryDeclaration() == null )
+			{
 				iter.remove();
 			}
 		}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/pst/ParserSymbolTable.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/pst/ParserSymbolTable.java
index a26381c5e60..6264c9ae74f 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/pst/ParserSymbolTable.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/pst/ParserSymbolTable.java
@@ -611,16 +611,26 @@ public class ParserSymbolTable {
 					while( iter.hasNext() ){
 						key = iter.next();
 						if( symbol.containsKey( key ) ){
-							ISymbol sym = (ISymbol) symbol.get( key );
-							if( !checkAmbiguity( sym, temp.get( key ) ) ){
-								if( data.mode == LookupMode.PREFIX ){
-									if( data.ambiguities == null ){
-										data.ambiguities = new HashSet();
-									}
-									data.ambiguities.add( sym.getName() );
+							Object obj = symbol.get( key );
+							Iterator objIter = ( obj instanceof List ) ? ((List)obj).iterator() : null;
+							ISymbol sym = (ISymbol) (( objIter != null && objIter.hasNext() ) ? objIter.next() : obj);
+							while( sym != null ){
+								if( !checkAmbiguity( sym, temp.get( key ) ) ){
+									if( data.mode == LookupMode.PREFIX ){
+										if( data.ambiguities == null ){
+											data.ambiguities = new HashSet();
+										}
+										data.ambiguities.add( sym.getName() );
+									} else {
+										throw new ParserSymbolTableException( ParserSymbolTableException.r_Ambiguous );
+									} 								
+								}
+								
+								if( objIter != null && objIter.hasNext() ){
+									sym = (ISymbol) objIter.next();
 								} else {
-									throw new ParserSymbolTableException( ParserSymbolTableException.r_Ambiguous );
-								} 								
+									sym = null;
+								}
 							}
 						} else {
 							symbol.put( key, temp.get( key ) );