When I click a link, e.g. in an email, Firefox opens two pages. One blank and one at the link.

If I click on a link in, for example an email, Firefox opens the linked page and also opens a blank page - usually on top of the linked page. I close the empty page and things then work normally until I use a link again. If I open Firefox from its icon it just opens my home page (about:blank) as usual. == This happened == Every time Firefox opened == a few days ago