There are too many variables to pick through.... on private computers, Windows keeps me logged in, Firefox keeps me logged in, and I've told the forum to keep me logged in. And the only time I go to the lounge is if someone posts a link to spam and doesn't mention it's the lounge, but I've not had to log in to get there either. So it ends up depending a lot on configurations as well.
There is a link to it in Win, but the actual lounge folder is in Mac. The folder is hidden to guests, but it's not possible to hide the link. Confusing terminology. The icon in the topic list is different for a link than for a folder, but I tend to call something you can click on a link regardless of technical differences.
Can you do a compare and contrast in your operating system and browser settings for remembering login info, as well as the cookies that control things? There has to be difference in there somewhere that's tripping it up.