New user activation does not work

Dear all,

I am trying to add a new user to one of my network sites.

The situation is as followed. The wordpress install is located in a subfolder called “beta”, the website itself uses main domain. e.g. http://www.domain.com and not http://www.domain.com/beta/

The website itself works perfect, also creating additional networksites.

Today i wanted to add a new user to our main site, the user did receive the invitation mail.

But clicking the link opens the main website, header… and then it stops. It looks like the plugins activated for the main site aren’t loaded either (like the are not activated).

Who knows how to fix this problem?