Hi Richard!
It seems that nobody responded to your question. It happened to me, too. At every time when I try UNDO, LV makes a General Protection Error. It is probable that my VIs were broken at some timing although I have nothing to recall. It went well till yesterday. I re-installed OS(Windows XP) and LV on my machine, but no effects. I have to bring them to my customer tomorrow. Quite a serious situation.
Michiro