I can't help you directly with your problem except to observe that I find it hard to believe that Search Incognito was officially recommended by Firefox. The name "Search Incognito" is usually associated with Google Chrome. While you are waiting for some more specific advice, do some research on your troublesome Mindspark Toolbar Platform Plugin. Google for information and removal advice. How did you get it? What do you use it for?

Could you describe where this shows up in more detail? In particular, could you check:

• Did this change your home page? You can check the setting on the Options page, General category. Startup, home page, tabs, and download settings

• Did this change your default search engine? You can select a different default on the Options page, Search category. Change your default search settings in Firefox

• Did this thing add one or more new extensions? You can view, disable, and often remove unwanted, nonessential, and unrecognized extensions on the Add-ons page. Either:
  • Ctrl+Shift+a
  • "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then cast a critical eye over the list on the right and, if in doubt, disable.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

If it comes back, there probably is an external component. In that case, you may need to take these actions before fixing your Firefox settings:

(1) Open the Windows Control Panel, Uninstall a Program. After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help surface undisclosed bundle items that snuck in with some software you agreed to install. Be suspicious of everything you do not recognize/remember, as malware often uses important or innocent sounding names to discourage you from removing it. Take out as much trash as possible here.

(2) You can search for remaining issues with the scanning/cleaning tools listed in our support article: Troubleshoot Firefox issues caused by malware. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case.

Thanks for everyone's responses. I also had initiated an inquiry to SI itself and received instructions on how to disable it.

What I got initially was a pop-up (apparently from Google Chrome) offering the installation and it did state that it was recommended by Firefox. I installed it thinking that it might be a good idea to eliminate tracking of my Google inquiries. However, it turned those inquiries into something like Ask.com (ie, worthless).

It also occurred to me that I might have just installed some malware so I will no longer be doing such installations in the future.

I'm not a "techie" and have no business taking such chances.

Nothing but "standard updates" from now on.

Thanks again to everyone.