Hi seekr, is there a movable divider between the left pane and the right pane? Or does the address bar have some address other than

https://outlook.live.com/mail/inbox

If so, that sounds like Outlook opened in the Sidebar, which is the same area, usually on the left, where you can view a list of bookmarks.

It's a bit difficult to open a website in the sidebar, but it can happen if a bookmark to the site is specially set to do that. If you used a bookmark to open Outlook this time, let's check its properties. Right-click the bookmark and choose Properties. Then look for a checkbox in the lower left corner labeled "Load this bookmark in the sidebar". If that has a check mark, uncheck it.

To get rid of the sidebar, if there's no close button, you can open your bookmarks or history there instead (try Ctrl+b or Ctrl+h). Those both have an X button to close the sidebar.

Hi jscher2000 - Not sure if my previous reply actually posted so let me repeat! You hit the nail on the head! After two futile days of trying to solve it, your solution worked. It was loading from a bookmark. The address was not the correct one you showed, and I could only widen the pane a small amount. The Properties did have the "Open in sidebar" checked. Unchecked, corrected the bookmark address, and all is well again. Don't know how it got to where it was, having used Hotmail and Firefox for many years.

My appreciation and many thanks for your insight and taking the time to resolve this. seekr