I've got remote app working for all users just fine. We all connect through a single gateway that allows access to all app servers. This worked well for months.
Recently 2 users can no longer use remote app. Every app (on any server) shows the login process, but where the app should appear, this is shown instead (http://imgur.com/RJuWa9H.jpg) (then times out 5 minutes later). This happens no matter the app, or the server the app is hosted on.
They can log into the servers via rdp normally (and through the gateway too), this is only when using remote app...
The only correlation is that these users are testing out webDAV in our environment... This is the only thing they have in common. The event logs of the clients, gateway, and app servers are all clean.