Gonna need a little more info on that. When I X out a browser window ( I use Internet Explorer usually here ) and come back later on, I am still logged into the site. I've X'd out and come back several times today with no issues.
Not aware of any changes to the site.
Are you sure it isn't your browser deleting your cookies?
Firefox has developed a strange habit in the past few days of not wanting to remember any of my passwords and also has wiped out all my playback settings for video, audio, etc. And it has logged me out of this site before.
But if anyone else is having the same constant issue, let us know here.