Cookies/Sessions Being Reset

[eluser]Bl4cKWid0w[/eluser]
I have used SMF's user system to integrate my site / forum. I want to be able to go back and forth from my forums to my main site and vice versa. However, everytime I try to do so, my cookies get reset. I go to clear private data on my browser and clear the cookies and it works fine. I know it's not on SMF's side because I help run a production forum that uses SMF and nothing happens there and they are the same versions with no mods.

Anyone have any ideas?