Keeps logging out

I am running 1.5.2. Safari. Tiger 10.4. For some reason, when I am in the admin, it sends me back to the login page to login again. Once I login it takes me right back to where I was in the admin. That fact makes me thing this is not an error, but its a weird occurance and I would like to find a way to stop it. I can’t find the same issue anywhere. Anyone else?