diff --git a/C/absmi.c b/C/absmi.c
index 1edb24337..3f8957519 100755
--- a/C/absmi.c
+++ b/C/absmi.c
@@ -1364,6 +1364,10 @@ static void
 undef_goal( USES_REGS1 )
 {
   PredEntry *pe = PredFromDefCode(P);
+  if (Yap_UnknownFlag(CurrentModule) == TermFail) {
+    P = FAILCODE;
+    return;      
+  }
   BEGD(d0);
   /* avoid trouble with undefined dynamic procedures */
   /* I assume they were not locked beforehand */
@@ -1373,9 +1377,7 @@ undef_goal( USES_REGS1 )
     PP = pe;
   }
 #endif
-  if ((pe->PredFlags & (DynamicPredFlag|LogUpdatePredFlag|MultiFileFlag)) ||
-      CurrentModule == PROLOG_MODULE ||
-      (UndefCode->OpcodeOfPred == UNDEF_OPCODE)) {
+  if (pe->PredFlags & (DynamicPredFlag|LogUpdatePredFlag|MultiFileFlag)) {
 #if defined(YAPOR) || defined(THREADS)
     UNLOCKPE(19,PP);
     PP = NULL;
diff --git a/C/flags.c b/C/flags.c
index beced0741..4c32ea845 100644
--- a/C/flags.c
+++ b/C/flags.c
@@ -613,8 +613,8 @@ static bool sys_thread_id(Term inp) {
 static bool setYapFlagInModule(Term tflag, Term t2, Term mod) {
   CACHE_REGS
   FlagEntry *fv;
-  ModEntry *new = Yap_GetModuleEntry(mod);
-  if (!new)
+  ModEntry *me = Yap_GetModuleEntry(mod);
+  if (!me)
     return false;
   fv = GetFlagProp(AtomOfTerm(tflag));
   if (!fv && !fv->global) {
@@ -641,18 +641,18 @@ static bool setYapFlagInModule(Term tflag, Term t2, Term mod) {
   // module specific stuff now
 
   if (fv->FlagOfVE == UNKNOWN_FLAG) {
-    new->flags &= ~(UNKNOWN_MASK);
+    me->flags &= ~(UNKNOWN_MASK);
     if (t2 == TermError) {
-      new->flags |= (UNKNOWN_ERROR);
+      me->flags |= (UNKNOWN_ERROR);
       return true;
     } else if (t2 == TermFail) {
-      new->flags |= (UNKNOWN_FAIL);
+      me->flags |= (UNKNOWN_FAIL);
       return true;
     } else if (t2 == TermWarning) {
-      new->flags |= (UNKNOWN_WARNING);
+      me->flags |= (UNKNOWN_WARNING);
       return true;
     } else if (t2 == TermFastFail) {
-      new->flags |= (UNKNOWN_FAST_FAIL);
+      me->flags |= (UNKNOWN_FAST_FAIL);
       return true;
     }
     Yap_Error(
@@ -661,13 +661,13 @@ static bool setYapFlagInModule(Term tflag, Term t2, Term mod) {
         RepAtom(AtomOfTerm(tflag))->StrOfAE);
     return false;
   } else if (fv->FlagOfVE == DOUBLE_QUOTES_FLAG) {
-    return dqf1(new, t2 PASS_REGS);
+    return dqf1(me, t2 PASS_REGS);
   } else if (fv->FlagOfVE == CHARACTER_ESCAPES_FLAG) {
     if (t2 == TermTrue) {
-      new->flags |= M_CHARESCAPE;
+      me->flags |= M_CHARESCAPE;
       return true;
     } else if (t2 == TermFalse) {
-      new->flags &= ~(M_CHARESCAPE);
+      me->flags &= ~(M_CHARESCAPE);
       return true;
     }
     Yap_Error(DOMAIN_ERROR_OUT_OF_RANGE, t2,
@@ -675,7 +675,7 @@ static bool setYapFlagInModule(Term tflag, Term t2, Term mod) {
               RepAtom(AtomOfTerm(tflag))->StrOfAE);
     return false;
   } else if (fv->FlagOfVE == BACKQUOTED_STRING_FLAG) {
-    return bqf1(new, t2 PASS_REGS);
+    return bqf1(me, t2 PASS_REGS);
     ;
   }
   // bad key?
@@ -684,7 +684,7 @@ static bool setYapFlagInModule(Term tflag, Term t2, Term mod) {
 
 static Term getYapFlagInModule(Term tflag, Term mod) {
   FlagEntry *fv;
-  ModEntry *new = Yap_GetModuleEntry(mod);
+  ModEntry *me = Yap_GetModuleEntry(mod);
   if (!mod)
     return false;
   fv = GetFlagProp(AtomOfTerm(tflag));
@@ -695,28 +695,28 @@ static Term getYapFlagInModule(Term tflag, Term mod) {
   // module specific stuff now
 
   if (fv->FlagOfVE == UNKNOWN_FLAG) {
-    if (new->flags & UNKNOWN_ERROR)
+    if (me->flags & UNKNOWN_ERROR)
       return TermError;
-    if (new->flags & UNKNOWN_WARNING)
+    if (me->flags & UNKNOWN_WARNING)
       return TermWarning;
     return TermFail;
   } else if (fv->FlagOfVE == CHARACTER_ESCAPES_FLAG) {
-    if (new->flags & M_CHARESCAPE)
+    if (me->flags & M_CHARESCAPE)
       return TermTrue;
   } else if (fv->FlagOfVE == BACKQUOTED_STRING_FLAG) {
-    if (new->flags & BCKQ_CHARS)
+    if (me->flags & BCKQ_CHARS)
       return TermChars;
-    if (new->flags & BCKQ_CODES)
+    if (me->flags & BCKQ_CODES)
       return TermCodes;
-    if (new->flags & BCKQ_ATOM)
+    if (me->flags & BCKQ_ATOM)
       return TermAtom;
     return TermString;
   } else if (fv->FlagOfVE == DOUBLE_QUOTES_FLAG) {
-    if (new->flags & DBLQ_CHARS)
+    if (me->flags & DBLQ_CHARS)
       return TermChars;
-    if (new->flags & DBLQ_CODES)
+    if (me->flags & DBLQ_CODES)
       return TermCodes;
-    if (new->flags & DBLQ_ATOM)
+    if (me->flags & DBLQ_ATOM)
       return TermAtom;
     return TermString;
   }
@@ -1012,6 +1012,21 @@ bool setYapFlag(Term tflag, Term t2) {
   return true;
 }
 
+
+Term Yap_UnknownFlag(Term mod) {
+     if (mod == PROLOG_MODULE)
+       mod = TermProlog;
+
+      ModEntry *fv = Yap_GetModuleEntry(mod);
+  if (fv == NULL)
+     fv = Yap_GetModuleEntry(AtomUser);
+     if (fv->flags & UNKNOWN_ERROR)
+      return TermError;
+    if (fv->flags & UNKNOWN_WARNING)
+      return TermWarning;
+    return TermFail;
+}
+
 Term getYapFlag(Term tflag) {
   FlagEntry *fv;
   flag_term *tarr;
@@ -1043,7 +1058,7 @@ Term getYapFlag(Term tflag) {
       Yap_Error(DOMAIN_ERROR_PROLOG_FLAG, fl, "trying to read unknown flag %s",
                 RepAtom(AtomOfTerm(fl))->StrOfAE);
     }
-    return FALSE;
+    return false;
   }
   if (fv->global)
     tarr = GLOBAL_Flags;
diff --git a/H/YapFlags.h b/H/YapFlags.h
index 03dbbfebe..7c349cdfa 100644
--- a/H/YapFlags.h
+++ b/H/YapFlags.h
@@ -359,6 +359,8 @@ static inline Term gcTrace(void) {
   return GLOBAL_Flags[GC_TRACE_FLAG].at;
 }
 
+Term Yap_UnknownFlag(Term mod);
+
 bool rmdot(Term inp);
 
 xarg *Yap_ArgListToVector(Term listl, const param_t *def, int n);
diff --git a/pl/boot.yap b/pl/boot.yap
index c65aa3677..6f8cbb383 100644
--- a/pl/boot.yap
+++ b/pl/boot.yap
@@ -253,15 +253,13 @@ private(_).
         '$iso_check_goal'/2]).
 
 
-   
+
 '$early_print_message'(_, absolute_file_path(X, Y)) :- !,
 	format(user_error, X, Y), nl(user_error).
 '$early_print_message'(_, loading( C, F)) :- !,
-    '$show_consult_level'(LC),
-    format(user_error, '~*|% ~a ~w...~n', [LC,C,F]).
+    format(user_error, '~*|% ~a ~w...~n', [2,C,F]).
 '$early_print_message'(_, loaded(F,C,M,T,H)) :- !,
-    '$show_consult_level'(LC),
-    format(user_error, '~*|% ~a:~w ~a ~d bytes in ~d seconds...~n', [LC, M, F ,C, H, T]).
+    format(user_error, '~*|% ~a:~w ~a ~d bytes in ~d seconds...~n', [2, M, F ,C, H, T]).
 '$early_print_message'(Level, Msg) :-
     source_location(F0, L),
     !,
@@ -269,23 +267,24 @@ private(_).
 '$early_print_message'(Level, Msg) :-
 	format(user_error, 'unprocessed ~a ~w ~n', [Level,Msg]).
 
-'$exceptional_cases'(_:print_message(Context, Msg)) :-
+ '$handle_error'(_Action,_G0,_M0) :- fail.
+
+% cases where we cannot afford to ever fail.
+'$undefp'([_|print_message(Context, Msg)], true) :- !,
     '$early_print_message'(Context, Msg).
- 
+% undef handler
 '$undefp'([M0|G0], Action) :-
     % make sure we do not loop on undefined predicates
     '$stop_creeping'(Current),
-    yap_flag( unknown, _, fail),
+    yap_flag( unknown, Action, fail),
  %   yap_flag( debug, Debug, false),
     (
-     '$exceptional_cases'(M0:G0),
      '$undefp_search'(M0:G0, NM:NG),
      ( M0 \== NM -> true  ; G0 \== NG ),
-     NG \= fail,
-    '$pred_exists'(NG,NM)
+     NG \= fail
 	->
      yap_flag( unknown, _, Action),
-  %   yap_flag( debug, _, Debug),
+       %   yap_flag( debug, _, Debug),
      (
        Current == true
       ->
@@ -296,11 +295,9 @@ private(_).
      )
 	;
      yap_flag( unknown, _, Action),
-%     yap_flag( debug, _, Debug),
-    '$pred_exists'('$handle_error'(Action,G0,M0), prolog),
      '$handle_error'(Action,G0,M0)
     ).
-    
+
 /*
 '$undefp'([M0|G0], Default) :-
     G0 \= '$imported_predicate'(_,_,_,_),
@@ -675,7 +672,7 @@ number of steps.
 	 Option \= top, !,
 	 '$current_module'(M),
 	 % allow user expansion
-	 expand_term((:- G), O),
+	 expand_term((:- M:G), O),
 	 (
 	     O = (:- G1)
 	 ->
@@ -1476,7 +1473,7 @@ bootstrap(F) :-
 %
 '$precompile_term'(Term, ExpandedUser, Expanded) :-
 %format('[ ~w~n',[Term]),
-	'$expand_clause'(Term, ExpandedUser, ExpandedI), 
+	'$expand_clause'(Term, ExpandedUser, ExpandedI),
     !,
 %format('      -> ~w~n',[Expanded0]),
 	(
@@ -1705,7 +1702,6 @@ log_event( String, Args ) :-
 	prompt(_,'    '),
     '$ensure_prompting'.
 
-
 /**
   @}
 */
diff --git a/pl/init.yap b/pl/init.yap
index 58a8a12c2..12f8750a0 100644
--- a/pl/init.yap
+++ b/pl/init.yap
@@ -133,11 +133,14 @@ otherwise.
 
 :- dynamic prolog:'$parent_module'/2.
 
+%:- start_low_level_trace.
 :- [
     'directives.yap',
 	 'preds.yap',
 	 'modules.yap'
    ].
+%:- stop_low_level_trace.
+
 
 :- use_module('error.yap').