nyc,
The AP-89DMR2 command is for an HP/Agilent RF generator and sets the output power to -89dBm and shuts off the output. That is just a safety portion so if someone turns the output on, it will be heavily attenuated. This command works fine and the instrument is very stable communication-wise.
jasonhill,
Thanks for the suggestion. At this point I believe the investigation is purely academic as several workarounds have been brought up and are successful. I wish the problem could be duplicated with NI-Spy running so that we could find the underlying problem, but I can't seem to get it to lock up while NI-Spy is capturing. However, the problem occurrs 100% of the time if I run the original vi alone.
Anyway, I appreciate all your help and suggestions.
jon
