A couple of questions and an answer: 1) Is this a NI USB-Serial convertor?
2) Are you unplugging the USB-Serial convertor or the serial cable attached to it? If you remove the convertor you are yanking a COM port out from under LabVIEW and this results in an unhappy application. I do not know of a way to fix this. If you're simply disconnecting the serial cable, the USB-Serial convertor should behave exactly like the build-in COM port. Which gets back to my 1st question (brand of your convertor?)
