Reactor crashing drawing

I am using the following code to attempt to modify attributes automatically. As soon as it hits the entmod line AutoCAD crashes
with:
"INTERNAL ERROR; !u:\global\src\ObjectDbx\DB\IMP\src\dbattr.cpp@466:eWasNotifying"
I thought the (if *reaction_flag* .. (setq *reaction_flag* nil) lines were supposed to cover this sort of thing. Is there some
other way that I should be going about this? I have spent a great deal of time trying to figure some way to make this work and am
out of ideas. Any suggestions and knowledge are greatly appreciated.
Thanks
Cliff

(setq block_name "ReceptacleDuplex")
(defun test ()
(setq att_req (getvar "attreq"))
(setvar "attreq" 0)
(princ "\nSelect insertion point: ")
(command "-insert" block_name "s" (getvar "dimscale") pause nil)
(princ "\nSelect rotation angle: ")
(command "-insert" block_name (getvar "lastpoint") (getvar "dimscale") "" pause)
(vl-load-com)
(setq reactor_block (vlax-ename->vla-object (entlast)))
(vlr-pers (vlr-object-reactor (list reactor_block) (list reactor_block) '(vlr-modified . attb_angle_right_reactor))))
(setvar "attreq" att_req)
)

(setq *reaction_flag* t)

(defun attb_angle_right_reactor (notification_object reactor_object parameter_list
/ attb_angle current_entity attb_list)
(princ "\n01\n")
(if *reaction_flag*
(progn
(setq *reaction_flag* nil)
(setq current_entity (vlax-vla-object->ename (car (vlr-owners reactor_object))))
(setq attb_angle 0.0)
(setq current_entity (entnext current_entity))
(while current_entity
(setq attb_list (entget current_entity))
(if (= (cdr (assoc 0 attb_list)) "ATTRIB")
(progn
(setq attb_list (subst (cons 50 attb_angle) (assoc 50 attb_list) attb_list))
(entmod attb_list)
(entupd (entlast))
)
)
(setq current_entity (entnext current_entity))
)
(setq *reaction_flag* t)
)
)
)