hi mike1313, this sounds like an issue with adware that is active on your system - a mere reinstall won't help in this case, so please perform all these steps:

1. reset firefox (this will keep your bookmarks and passwords)
2. afterwards go to the firefox menu ≡ > addons > extensions and in case there are still extensions listed there, disable them.
3. finally run a full scan of your system with different other security tools specialised in adware removal like the free version of malwarebytes and adwcleaner.

Troubleshoot Firefox issues caused by malware

Hi Philip,

I checked the addons and didn't see an issue (recognised all, most were 'ask' as well). Downloaded malwarebytes, ran, it, all the issues identified were not malware but deleted them anyway. Result, it hasn't popped up again.

Thanks for your assistance, regards, Mike