I have a tech sitting opposite so I asked him about this and he said the following:
Vbulletin allows user timeout. This is typically set low (i.e. a few minutes). Normally this can be overridden by a cookie (what the remember me box does)
If you have this box checked and it's not working it's likely one of three things:
- Your browser is not set to accept cookies
- You are browsing in "private mode" or your browser is not set to store history
- Your browser is set to clear history on exit and is clearing the cookies down on every tab/window close. Common in shared sites like schools/libraries etc...
- Some browsers have a "resubmit info on refresh" setting that is set to off. This will ignore the cookie and prompt for credentials on every page refresh for some vbulletin installations
Hope it helps someone..