That's a tricky one Wayne, I've never been able to get to the bottom of exactly how it works and what it calculates on.
For me it generally works pretty accurately, but not always. If you do NOT logout it doesn't know for sure that you are "gone" - in theory it is supposed to know that your activity has ceased and record that after a certain period.
A search on the topic to confirm my memory comes up with a lot of conflicting information and ideas - it seems to be a major source of confusion among admins!
IN THEORY, according to a vB developer:
- User logs in. Lastactivity is updated. All posts since lastvisit are unread.
- User clicks on a forum. Lastactivity is updated. Lastvisit stays the same.
- User continues to browse forum pages. Lastactivity is updated on every page load. Lastvisit stays the same.
- User goes inactive. After the user has been inactive for the length of the cookie timeout, their last visit date is updated.
- Or if the user logged out instead of going inactive then their lastvisit would have been updated upon logging out.
IN PRACTICE there is much debate on whether it really works like this, and on which versions it works like this!
Try logging out every time you leave and see if it works better for you. Another time-honored suggestion is to clear all your cookies and start again, but I hate doing that myself.
Sorry I can't be more help!