diff -upr old/sc/source/core/tool/interpr1.cxx new/sc/source/core/tool/interpr1.cxx
--- old/sc/source/core/tool/interpr1.cxx	2008-02-25 10:02:14.000000000 +0800
+++ new/sc/source/core/tool/interpr1.cxx	2008-03-10 14:08:14.000000000 +0800
@@ -2259,7 +2259,11 @@ void ScInterpreter::ScN()
 {
     USHORT nErr = nGlobalError;
     nGlobalError = 0;
-    double fVal = GetDouble();
+    double fVal;
+    if ( GetRawStackType() == svString )
+        fVal = 0.0;
+    else
+        fVal = GetDouble();
     if ( nGlobalError == NOTAVAILABLE || nGlobalError == errIllegalArgument )
         nGlobalError = 0;       // N(#NA) and N("text") are ok
     if ( !nGlobalError && nErr != NOTAVAILABLE )