sampapa12, I wonder if something at system start-up is opening a link? So it is not Firefox itself that is starting as such, but something is opening a link at start-up and it is being opened in Firefox as that is your default browser? I would first run a full system malware scan in case these ads are being triggered by a piece of malware. If the scan finds nothing then Something else you could try is to check your OS start-up items and see if there is anything there that you do not recognise or that might launch an ad at system start-up.