Hi Crippled ... I just found that you had responded on this forum with notices in my spam folder this morning. Please forgive me for the long delay in answering your post.
I met with my tech yesterday and he explained what I was seeing and how this "scareware" worked. (btw ... I like your name for it, Ransomware.) It appears that there is code embedded in the error message page that disables the user's mouse so that an uninformed user, me, would think their computer was locked. It's not. It's only locked as long as that page is open.
The fix was quite simple. Closing down the computer completely and then re-booting and opening FF brings up a page from FF saying that they are "embarrassed because they cannot open the browser" and a list of the pages that were open the last time the browser was in use. That list included all of the tabs I had open when the scareware message popped up and "locked" my computer. The list included the page for the scareware. Unchecking all of the boxes and then clicking the RESTORE button at the bottom of that page allowed FF to go back to a point prior to where it was before the scareware page appeared.
At that point FF was completely functional again because the scareware page did not open. There was no need to reinstall FF.
R did run scans to check my computer to see if there were any problems and my computer was totally clean.
This particular scareware does not really compromise the browser and does not get past the firewall or the virus protection I already had loaded on the computer. You can see the print screens on my post above to see what scareware I was dealing with this week. I am not certain that all scams of this nature work this way, so I have copied your advice for future reference. Thank you.
I have since purchased an external hard drive to back up my computer so that I don't go into a panic mode if I cannot get help immediately.