franlambert said

Now I have a dialogue box which tells me my extension has expired

Expired? What add-on is this? Where did you get it from? Is this an extension, or a plugin? Any extension can be removed from the Add-ons Manager. A plugin is a program Firefox finds already on your system. The only way to remove a plugin is to remove its program.

Extensions or plugins can be disabled from the add-ons Manager.

The "extension" if that is the name for it is an extension which claims to be able to access my e-mail account quicker and works by forwarding my attempts to get to Firefox by diverting me to mymailxp.com The introduction to this came when I clicked on Firefox and it seemed to be offered as a genuine Firefox extension. When I found out I could only get the US version of Firefox as a browser on it, I uninstalled it. But when I downloaded Firefox again, there it was. Now it will not let me access Firefox unless I renew it, which I emphatically do not wish to do, and it does not respond to an uninstall request.

Where did you get your Firefox? Follow these directions;

Download Firefox For All languages And Systems {web link} Save the file. Then;

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86) Mac: Open the "Applications" folder. Linux: Check your user manual.

Look for, and rename any Mozilla or Firefox folders by adding .old to them.

After rebooting the computer, run a registry scanner. Then run the installer. If all goes well, remove the OLD folders when you are done.

If the problem is still there,

Refresh Firefox {web link} is a LAST RESORT ! !

Refresh Firefox - reset add-ons and settings

If you're having problems with Firefox, refreshing it can help. The refresh feature fixes many issues by restoring Firefox to its default state while saving your essential information like bookmarks, passwords, and open tabs.

Dear Fred McD, Thanks for your advice but I'm afraid none of this works. 1. When I download Firefox afresh the mymailxp.com extension automatically attaches to the new download and I get the same "extension expired" rubric when I try to open Firefox. One of the apparent problems I have is that there is no dialogue box on the download which gives a "save" option - just "run". 2. I have marked the "old" Firefox program with .old as instructed but it will not respond to an uninstall instruction. 3. I have run a register scan, a regular anti-virus scan and a malware scan and none of these find anything. However, I have searched mymailxp.com on Google and am told that it is a browser hijacker by the following link https://malwaretips.com/blogs/remove-search-myemailxp-com/ which also posts comprehensive instructions on how to get rid of it (16 pages!). I will follow this and let you know how I get on.

it seems almost like a virus first remove it from the firefox addons and then go to control panel and add and remove look up there for this app and uninstall it from there and get start your firefox if still it exist delete it from addons and restart the firefox your problem should be fixed

otherwise save your saved passwords and bookmarks and restore your firefox

Malware type programs like to leave something behind.

You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.