RitchB-PA said

accidentally refreshing the bookmarks (from toolbar)

What do you mean by this?

Now it opens with a series of black boxes with details showing

Hello,

In order to better assist you with your issue please provide us with a screenshot. If you need help to create a screenshot, please see How do I create a screenshot of my problem?

Once you've done this, attach the saved screenshot file to your forum post by clicking the Browse... button below the Post your reply box. This will help us to visualize the problem.

Thank you!

Places Maintenance {web link} Allows to run Maintenance tasks on the database that drives Places, the bookmarks and history module behind Firefox.

Open the Add-ons Manager. Locate the add-on and press the Options button. Then follow the directions.

I appreciate the answers, but I wasn't able to "carry them out". I have a screenshot, which is attached. I downloaded Places Management, but don't know what to do next. I do know something about a computer, but obviously not enough, sorry.

RitchB-PA said

I downloaded Places Management, but don't know what to do next.

FredMcD said

Open the Add-ons Manager. Locate the add-on and press the Options button. Then follow the directions.

I do know something about a computer, but obviously not enough, sorry.

Whatever you know today is obsolete by tomorrow  :-)

About the issue, does that happen only with the bookmarks pulldown, or do the others do the same thing?

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

It goes away in Safe Mode.

See this: https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode#w_the-problem-does-not-happen-in-safe-mode

After all the help, the problem appears to be AdBlocker. Thank You!

Please contact their support and let them know. Forum; Adblock Plus Homepage {web link}