All the information given here is of course correct – verisign is a reputable company issuing SSL certificates.
Did you copy and paste the banner from Poker Champs?
It has happened to me before also with a different program that had a SSL certificate installed, for some reason the banner would pop the certificate notice the first time you visited the page it was on. Very strange and I have no idea how this happens, but in any case it is not the first time I hear of this. It only happens with copied and pasted banners…
The ad from RedNova above does come with a once daily pop about some alert – it is an ad for a spyware remover and launches once per day per person.
Poker Champs is not a problem per se – they need to do something about their deal with Verisign is all. And they should provide hosted banners if they have a problem with the SSL popping on affiliate sites.