"There are ways to make a comm port snooper using TWO comm ports on a 2nd PC. You can do WEB searches and find informaton for doing this (i.e. how to build the special cable required and find the capture software)."

If you've got a USB-to-serial (RS-232) adapter, it may come with a snooper built in. For example, I have a Keyscan High Speed USB Serial Adapter (USA-19QW) for one of my laptops. The software provided with it has a diagnostics window with a "data monitor". Sort of a poor-man's protocol analyzer, displaying time-stamped serial events as they occur. It has come in handy when I didn't have my "real" protocol analyzer with me.