I have just changed from my old Win XP & Thunderbird 45.5.0 to a much more powerful machine with Win 7, installed Thunderbird 60.6.1 then transferred my profile and email files. This worked very well for a few days, allowing me to click on File then Print Preview in order to check print appearance and to alter the Zoom factor to achieve the results I desire. This has changed so when I click on File then Print Preview, a preview pane appears to pop up momentarily, but immediately vanishes before I can either inspect it or change the Zoom factor. It was Ok when I first installed this version a few days ago. I notice several answers to Print Preview question mention CCleaner. This is installed and I think I may have once allowed its request to clean after closing Firefox. But that is not Thunderbird. Have you any suggestion please? Thanking you in anticipation.

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