This probably doesn't have anything to do with your crash, but thought I'd report it.
I was getting a similar "instruction referenced memory" crash every few days, and also a "could not communicate with port" error. It would work for a while and then get one error or the other
My original Vantage Pro Weatherlink connects through a serial to USB converter with the FTDI chipset. I have another USB device that's self-contained but appears as a serial port with the same FTDI driver.
I noticed that both drivers were set to 9600 baud. I knew the Vantage Pro was at 19,200.
Well, I set the Vantage Pro to 9600 and haven't seen either error in three days. Wonder if the two devices were confusing the driver.
Hope this doesn't jinx it.