I have (had) the same problem with Windows 2000 and Raduga closing down by itself. I think it must have something to do with the Windows memory getting full after a certain amount of time. (I heard something mention about a thing called Windows 2000 "memorylix".) So, I now close down and restart the PC once a week to avoid Raduga closing down on it's own at an unexpected (and unwanted) moment. This seems to work well.