Hi Diego,
In my testing with related sites mode and folder child sites, when I log into either site it logs me into all sites.
I was able to reproduce the problem with the file manager. I can fix this for the next release, but I think you can work around it by creating a text file at
/lang2/Services/FileService.ashx
and put this as the content of the file:
<%@ WebHandler Language="C#" Class="mojoPortal.Web.Services.FileService" %>
Best,
Joe