Thanks again, fransknorge.

That description of how to turn off javascript was clear and simple. Unfortunately, turning off javascript breaks the Forum Tools dropdown menu, which I believe I need for the Mark This Forum Read command. It seems that FlyerTalk, like life, has trade-offs.

I'll stand by my assertion that I do not have Flash, since it does not appear in the list of Add-ons. There is no cog icon at the top-right of the browser, perhaps because I'm on a Macintosh. There is an icon with three horizontal bars. Clicking it generates a pane with a cog, but that opens Preferences. There is also a jigsaw puzzle piece icon that opens the Add-on Manager, and that is where I find no trace of Flash.

I appreciate the hints.