I still have a very similar problem.
I have installed plex from the app-store on 05/05/2014.
I then installed some more apps and encountered strange dns behaviour. They were solved after a yum -y update.
From the dashboard, the link
http://plexms.at.home/ brings me to
http://plexms.at.home/index.html which is a sign in/sign up screen. Signing in, I find a plex client not connected to my plex server. I still don't really understand where this comes from.
Using the url
http://hda:32400/manage, I am redirected to
http://hda:32400/web/index.html where my server and its files are visible.
The links on the dashboard for the other apps are working well.
The behaviour is the same with FF or IE.
I didn't implement any workaround, as this is a limited (but annoying) issue but hopefully it might help getting to the cause of the issue.