Are you sure it’s the data receiving which is stopping your machine?
It seems to me that receiving data over a serial connection (at 9600baud) shouldn’t stop WD from responding, but someone else with a better knowledge of these things might have something to say about this.
I can only tell you that I’ve experienced something similar, but with me it was every 5 minutes. It happened to be that I had told WD to to a lot every 5 minutes (and it dutifully did). Every 5 minutes WD seemded to stop responding. I could reschedule a lot of the tasks, and now it isn’t a problem anymore,
You are sure you haven’t told WD to do a lot of stuff every minute? Or maybe it does, without telling you to do so (I just read: http://discourse.weather-watch.com/t/11763).
The above doesn’t help you that much, as I understand you can’t really do anything in WD as it keeps stopping responding :(. Maybe there are settings in the INI-file (or the .REG) you can try to alter, but I don’t know enough of the inner workinsg of those to be of assistance, I’m afraid. Sorry. 
Succes,
Chow.