I've been using Rainlendar for a couple of years now and love it. I just installed Vista on January 30th. I've noticed that some kind of event in Vista will cause Rainlendar to vanish from the desktop. It's still running, but it just disappears. I've been killing the task in Task Manager, then restarting it. I've tried the different position options, such as Normal, On Bottom and On Desktop. On Bottom created a huge solid color background behind the calendar, as if it were a hole in the wallpaper.
I found another thread with a similar
issue, but not quite the same. Just to be on the bleeding edge, I adding my Email address to the notification list for new releases.