I had the same problem
on another machine with an upgraded 9.2x profile on 9.52 (and probably any 9.5x version) Basically, in summary, you login to the main page, but when you click on one of the 'sections' (i.e.,
'yro.slashdot.org') your cookies don't follow you for some reason.
Since you won't find the solution to this anywhere else I'm going to post it here: the solution is to delete your Opera profile and let Opera re-create it. Not my favorite solution, but it works.