I want my Zap2it cookies, accept them and keep them. Y'all might can have some cookies, but no Zap2it cookies.
Not sure any of this will help in the long run... and I don't specifically know how you have your Options set up in Firefox ... specifically the Privacy area nor do I know what extensions you have that may mess with cookies... but I will say this....
Long ago I used Cookie Monster and it seemed to take a lot of work in dealing with it and the pages that I was on... all I wanted was to accept cookies for sites and/but keep those cookies for special sites ... and have the other cookies removed when I closed a tab... what I did was this... and BTW it's worked out perfectly... with no loss of any important cookies...
I first removed Cookie Monster, cleared out ALL my cookies, installed the add-on Self Destructing cookies and then proceeded to visit all the sites where I wanted to always keep cookies and when doing that the extension has (via its icon) the option to always keep those cookies. I just clicked on that option and for all of them... and that was all that I had to do.
Now, when I visit any site... sites like my bank, or in this case the TV site...the cookies are there... all others are gone when I close the tab... or Firefox.
Self-Destructing Cookies :: Add-ons for Firefox
You could always create a test profile and load that extension and play with it... see what you think.