Recently I've had to login every time I come to the forum (once a day probably), is it because I use 2 computers?
Yes. It stays logged in only on 1 pc, if it detects you are logged in on another pc, it logs you out automatically... This is the right way to do it. Even amazon etc do this, except that they fake log you in(using cookies).BUT If you try to do anything account related, then you suddenly have to log in again.