Why does this site keep logging me out, and can I change it

I seem to be being logged out, with a dialog box putting up “Refresh” every 2 or 3 minutes. Hardly time to browse one or two topics. Can I stop it doing so, nothing appeared to be in the preferences section.

I’m not sure, it’s only just started happening …

Just after I posted this I saw a message saying the overall site was having problems. But as a newbie I didn’t know it wasn’t normal.