ossobuco wrote:... A huge number of hours of work are going into setting up the new system and keeping this one running, in large part by volunteers. ....
100% by volunteers, actually.
And developers are working on a new A2k. This not only is (most likely) causing your login issues but it is also, on occasion, resetting people's "new posts" pages. They do work, they refresh the database, and it does the reset. That is my understanding of what is happening.
I am sorry that it is happening to you. Since it appears to be happening to you more than others, it's prudent to check things from your end. Checking for spyware, etc. is helpful for your system, anyway. You may also want to check things like security settings, whether you are getting cookies, etc. All the usual suspects. I hope that this is of help to you.