Allen, I tried using registry monitor programs, but I am not seeing different there. Whatever the difference is about the function setdefaultprinter, its not in the registry. That much I can confirm.
I cannot use the process monitor to see whats happening when I attempt to print from that program after using setdefaultprinter because the print command and button is greyed out. Never fear, I will research the issue and see if I can track down what causes it.