New window (Command N) is now opening a new window with a dozen or so old tabs.

Hi, Now when I do a Command N, a new browser window is opened, but I always get the same dozen or so tabs that open. This did not use to happen and I do not recall changing any settings. I can close all those tabs, close the window, and when I open a new window again, that tabs are all back. Thanks so much, Charlie PS Yes. It's driving me crazy. :-)