hello dominic, this sounds like a problem possibly caused by adware on your pc. please go to firefox > addons > extensions & remove any suspicious entries (toolbars, things that you have not installed intentionally, don't know what purpose they serve, etc). also go to the windows control panel / programs and remove all toolbars or potentially unwanted software from there and run a full scan of your system with the security software that you have in place and different other tools like the free version of malwarebytes & adwcleaner.

Remove a toolbar that has taken over your Firefox search or home page Troubleshoot Firefox issues caused by malware

afterwards install the search reset addon - it will revert the most common customizations those adware programs do in firefox back to the default: https://addons.mozilla.org/firefox/addon/searchreset/

Sweetpacks is the most pernicious piggyback on freeware I have encountered.

I used Malwarebytes and CCleaner to get rid of anything with "sweetpacks" in the name or publisher.

Then to make Firefox stop opening Sweetpacks every time I opened a new tab:

1. In the address bar, type 'about:config' and then click Enter. 2. You will be notified that you are about to change your settings. Click 'I'll be careful, I promise!' 3. You will see a Search field, type ‘newtab' and then click 'browser.newtab.url'. 4. In the box that will be opened, enter the URL that you want to open in the new tab page instead of Sweetpacks and then click OK.

I had the exact same Sweetpacks problem and after uninstalling and reinstalling Firefox plus doing a system restore plus running Kaspersky Internet Security,it was still there.Finally I ran a full scan with Malwarebytes Pro and it came up trumps with 15 Sweetpacks entries which it quarantined and which I subsequently deleted.Sweetpacks-all gone.Malwarebytes Pro is worth the money.