thanks for the advice David, and everyone else.
It is really strange because Firefox remembers the login name and password but I have to manually click ´log in´each time, and I rarely close firefox and at the moment have multiple tabs open all the time from this forum.
I have set firefox to remember history so it is accepting all cookies (i believe anyway, this option removes the cookies options). I have also tried deleting existing cookies from here and logged in again but still the same result.
It's not an issue really, I don't mind just pressing 'log in' each time i visit. I'm thinking maybe it is something to do with an add-on I have installed, maybe adblock plus or something. But nevermind, no big deal really.