So you decided that you only want a simple template for your site-collection. But then after a couple of days you want to active the feature Office SharePoint Server Publishing, so you can do some WCM stuff. What happens when you do that? Well this happened to me : Then what you do? Well being the google-depended person I am, I found the solution ;) Instead of using the webinterface, we must use our good ol' STSADM!
stsadm -o activatefeature -id AEBC918D-B20F-4a11-A1DB-9ED84D79C87E -url http://mysharepoint.comMuch kudos to Tariq ! Thanks mate :)