Hi,

For some reason when I log in as a user the log out button (Link) is missing so users can't log out?

Why is this and how can I resolve it?

Thanks,
Adam.

Is it in the block "Usermenu" that the button is missing?
Is the other links available in the menu (Administration etc.)

It's somewhat dependent on the theme. The way the system is designed OOB, when a person is logged off there is a login block on the pages and they can login. Once logged in, there is a User Menu block which shows the logoff link. Many themes have incorporated code which checks to see if the user is logged in or not and shows either login area or logoff depending (and then turn off the login block), and that code is readily available here on this site and so themes that don't have that can have it easily added.