If you are getting more than one per Pelican session it's because your browser security settings are not returning the cookie necessary for the website to know that you're already signed in.
You can use that same setting, but set pelican as a trusted site to allow that cookie.
OR
Go to
www.winfiles.com and get MrPopperStopper. It's a free program that kills all popups. It will also kill the ability to open a new window from a link within the existing one by default. To enable that per "click" you click on the taskbar icon to "allow the next popup".
I did find the Pelican Popup frustrating... My work computer has a higher setting and I would get 10-20 per forum session.