I typically use www.heavens-above.com in conjunction with StarryNight to plan an ISS viewing session. Most of the time they both agree very closely, but tonight (6-13-2011) StarryNight's track of the ISS was way off both from observation and heavens-above, and tomorrow night's (6-14-2011) track differs wildly from what heavens-above predicts. I believe I have StarryNight set to check for updates, it tells me when I launch it whether new data files were downloaded or not. Am I missing something?
ISS track in StarryNight not correct