Pprune login
A few days ago I started to have a login problem.
At the start of a 'session' I log in, everything proceeds normally, I can access threads etc.
Then, when I want to go to say page xx in an xxx page thread I get a message "Sorry, you have to log in...." I log in again, I get the 'you have successfully...' message and than this reverts to "Sorry..."
Backtabbing to the thread I can still see me as being logged in.
What's going on?