Security Issue: Update your Flash Player Version 18.0.0.232
https://www.adobe.com/products/flashplayer/distribution3.html Note: Windows users must download the “Internet Explorer” and “Plugin-based browsers” installers.

Note: Edge on Win10 does not use ActiveX version but its own Flash.

See if there are updates for your graphics drivers https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

Move your mouse to the area where the add-on icons are. Right click and select Customize. Or press the Alt or F10 key bring up the tool bar, Select View > Toolbars.

Look for Show / Hide Toolbars at the bottom left.

There is also a Restore Defaults button at the bottom middle.

Note that the OP in on Mac OS X 10.5, so can't update beyond Firefox 16 and use current Shockwave Flash versions.

You can use one of these to set which toolbars to show.

• View > Toolbars > Navigation Toolbar
• Right-click empty toolbar area

Just to confirm, this problem is in Firefox 16 running on MacOS X 10.5 ?

For security reasons, it would be best to switch to another browser that is being kept up-to-date, but I understand that options may be limited for your OS.

But back to the question at hand... Could you test in Firefox's Safe Mode? Here's how:

If Firefox is not running: Hold down the option key when starting Firefox. (On Windows, the Shift key)

If Firefox is running: You can restart Firefox in Safe Mode using either:

Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Reset or Refresh, and not making any permanent changes).

Any difference?