I have heard from members, and now experienced it myself. The forum asks me to log in, and when I click on a link it logs me out and states required log in. V 1.4.0
I had this happen recently after installing cloudflare, when I put my website into the cloudflare setup it got put in as z35spot.com and my site is registered at www.z35spot.com. If I forced my browser to z35spot.com (without the www) I could login successfully. I uninstalled cloudfare, that released the login from the non-www site and I was able to login again. Dont know if this helps or not but it sounds like the same symptoms i had.