In reply to G4OIG:
the system does not reset after each activation is entered
It works for me! Using Firefox 12.0 on an XP SP3 machine.
After logging in I waited 9m45s before clicking any links either on the menus or on the pages and I was still logged in. Then I entered an activation. Entered one line and hit add then waited 9mins before entering the next line. Still logged in. Another line, waited 9mins, still logged in, line OK. If I waited for too long then yes, I got an error, which needs cleaning up a lot, and had to log in again where I could continue with the activation.
But, the system does appear, from a statistically valid sample of 1, to do exactly what it’s meant to Gerald, wait upto 10 mins of non-activity between pages before timing out. So if you are getting logged out for waits of less than 10mins then it is either something your end or something happening at the hosting service outwith my control (server reboots etc.)