Index: /trunk/ccl/lisp-kernel/thread_manager.c
===================================================================
--- /trunk/ccl/lisp-kernel/thread_manager.c	(revision 4960)
+++ /trunk/ccl/lisp-kernel/thread_manager.c	(revision 4961)
@@ -545,5 +545,9 @@
 #endif
 #ifdef X86
-  tcr->lisp_mxcsr = (1 << MXCSR_DM_BIT) | (1 << MXCSR_UM_BIT) | (1 << MXCSR_PM_BIT);
+  tcr->lisp_mxcsr = (1 << MXCSR_DM_BIT) | 
+#if 0
+    (1 << MXCSR_UM_BIT) | 
+#endif
+    (1 << MXCSR_PM_BIT);
 #endif
   tcr->save_allocbase = tcr->save_allocptr = (void *) VOID_ALLOCPTR;