I've just purchased the express edition of Active Forums, but the friendly url option is disabled and set to "No".

<a href="http://www.activemodules.com/DesktopModules/ActiveForums/viewer.aspx?portalid=0&moduleid=398&attachid=7896" target="_blank"><img src=http://www.activemodules.com/DesktopModules/ActiveForums/viewer.aspx?portalid=0&moduleid=398&attachid=7897 border=0 /></a>

How do I enable this?

Make sure you are viewing the control panel as a host user, and not on a child portal.

hmm.

Ben, don't you have to be using sql 2008 or something to use that feature?

Good point Frozen. You do have to be running IIS 7. If not, it would also be disabled.

Resolved, it was a problem with not loggin in as host. Thanks for the responses!

I have IIS 7 now. I am already using the vanity urls. Do I have still have to add something to the web config file? I see a link asking me to enable the Friendly Urls in the Forum Control Panel. But when I click it (I suppose it is adding the required code in the web.config) it just keeps doing it's thing and then nothing changes.

What am I doing wrong?

Thanks.

You already made sure you are logged in as host, and you are not on a child portal?

Yes.