There are several subsites which Anonymous has access to, but some subsites can't be opened by Anonymous, because a popup comes up prompting Anonymous to login.
The curious thing is that Anonymous can open the subsites without problems if an user who is logged in has opened the subsites before. Then Anonymous can access the subsites for 30 minutes I think.
Any idea what is the problem here? I am more the frontend developer, but for me it looks like something on the server will be cached why Anonymous can then access the subsite.
The subsites are part of an intranet site based on the Seattle template so far I can say it.