Since the latest update (about a month back), Plarium website pages related to login/log off has been erratic.When I press "Log off" followed by "Yes" to the confirmation dialogue, the page takes forever to load or may not load at all and I end up with a black screen. I can easily say it happens 50% of the time at least. I can refresh the page and everything is back to normal again. So Basically, you can log off fine, but you cannot log in again because the page with the "Login" button usually get stuck loading or takes a considerably long time to do so.
As for people who cannot login after a logout, this is probably because they use multiple accounts. Plarium has limited the number of logins per machine (or IP), I think it is 4-5 every 1 or 2 hours. So if you just connected 4-5 accounts, on the 6th account forward you will start getting the error "Connection Lost". You just need to wait for an hour or two if you have the time, or simply find yourself another game to play, if cannot align this game with your available play time.
I agree that recently, the game is not as fun to play, and the amount of failures that do not get rectified in due time has outgrown the game updates and has been accumulating for a long time now.