I am so very grateful to you for your help. Now I have another issue: When I close Pegasus, I get the message below:

Looks pretty straightforward - just choose the "re-index" command, and let Pegasus fix it. Problem is that Pegasus responds that it "cannot reindex a folder that is currently open" . I did not open the folder, and I have been unable to figure out to "close" it. (I tried clicking on "Close all open trays" - all this did was to freeze the display May I throw myself on your mercy again? How do I close the offending folder so it can be reindexed?

There's a tool in Pegasus Mail's \programs\ subdirectory (supposed you have the default installation, it's the one containing "winpm-32.exe" ) allowing you to reindex folders while Pegasus Mail is closed: It's name is "mbxmaint_ui.exe". The path information you need (new mailbox location) can be taken from Pegasus Mail's Help => About Pegasus Mail => Info screen.

It looks like you have two problems. Not only does the folder need reindexing but it is hidden when open. If you have Pegasus Mail configured to save the desktop state between sessions then it is likely opening every time you start Pegasus Mail but is out of view. The "Window " pull down menu contains a list of all open windows. If it is listed, close all other windows to see if it becomes visible. If it doesn't, go to Window > Tile and see if that makes it visible.

Brian was absolutely right, going to the Tile display revealed the offending folder, (which appeared on the list on the left side of the screen, and was readily accessible in the first place). Clicking on the X on this screen apparently "closed" the folder, and right clicking on the folder resulted in a successful reindexing, (in a fraction of a second). All fixed now - except I can't figure out how to turn off the Tile display. (This flashes by when I start Pegasus, but seems to be hidden behind the main display Or has this been here all along, and I simply never noticed?) (I do not pretend to understand what is going on here, in terms of "open" windows. But perhaps there is no need to know...)

Again I am most grateful for all the help you are so generous with.

If you have Pegasus Mail configured to save the desktop state between sessions then it will start with the same folders open, each with its same windows size and position. If you like like that feature then just open all of the folders that you will want opened on each startup, resize and reposition each window to where you want then close Pegasus Mail to save that desktop state. One subsequent startup the open folders and window positions should be as you set them. You can lock this by turning off the save desktop state option or leave it enabled if tend to change things periodically. Keep in mind that the save desktop state function does not behave well when the Pegasus Mail main window is maximized. It is best to stretch it to full screen rather than run it maximized.