"Warning: Unresponsive plugin" ? ON EDIT: How do I uninstall & reinstall Firefox? [View all]

(Well, now/this-instant another kind of problem: No cursor marking where I'm typing!)

Something is going on. It started just after going to the Ancestry.com site, clicking on their various graphics. I'm not blaming, just saying that that was the last site I visited before the problems started. Did they insert a Cookie?

So the plugin problem: Getting a frozen screen, every few seconds the "Warning/unresponsive plugin" pops up; after a few times, then a popup offers the options of Debugging / Continuing/ Stop script.

Sometimes the Stop Script button works and allows proceeding to normal navigation.

I tried searching This PC for "plugins" and only got a list of Windows plugins. I thought this might be something like Temp files that needed to be cleaned out.

Oh, my cursor is back. What's going on here?