diff -ruN ccl-1.7-old/lisp-kernel/x86-exceptions.c ccl-1.7/lisp-kernel/x86-exceptions.c
--- ccl-1.7-old/lisp-kernel/x86-exceptions.c	2011-12-06 21:42:28 +0800
+++ ccl-1.7/lisp-kernel/x86-exceptions.c	2011-12-07 11:54:57 +0800
@@ -2067,10 +2067,15 @@
     return EXCEPTION_CONTINUE_SEARCH;
   } else {
     TCR *tcr = get_interrupt_tcr(false);
-    area *cs = TCR_AUX(tcr)->cs_area;
     BytePtr current_sp = (BytePtr) current_stack_pointer();
     CONTEXT *context = exception_pointers->ContextRecord;
-    
+    area *cs = NULL;
+    if( !(tcr && TCR_AUX(tcr)) )
+    {
+      return EXCEPTION_CONTINUE_EXECUTION;       
+    }
+    cs = TCR_AUX(tcr)->cs_area;
+
     ensure_safe_for_string_operations();
 
     if ((current_sp >= cs->low) &&