vbulletin will NOT automatically log anyone out as long as they ticked the remember me box, thats what its there for.
if your users are getting logged out, then thats a issue your b-z & c-s are causing.
I really appreciate the help... this is useful information that I will pass on to my programmers.
B-Z and C-S don't automatically log me out - only vbulletin... that issue stopped when I set the timeout to 90000. I set it back to 900 as you suggested because you seem to know what you are talking about.
Unfortunately, I expect vbulletin will start automatically logging me out again... for some unknown reason. Thanks for your help and hopefully ill be able to figure this out soon.