User Published Apps sessions hanging on Windows Server Splash Screen

Need to bounce an idea off of someone with extensive troubleshooting experience in the area of Citrix.

I have a production farm which sits behind Netscaler which points the users to StoreFront and then to separate backend Windows 2008 R2 XenApp 6.5 servers.

Recently, we have been getting reports that users are able to login to Citrix and then when they launch an application it gets stuck on the backend servers splash screen.  The application never launches.

The tricky part is it is only affecting a few people, everyone else is fine.  Doing some research on their connections, they are hitting the same backend servers as everyone else and is not defined to a single box.

The Citrix Receiver client they are using is the same as everyone else, 4.12.

I am investigating Domain policies, but wondering if there is something else related to their specific client?

I'm looking at the traffic flow from StoreFront to their client, etc... but so far nothing stands out.

Thanks in advance.

I have cleared their roaming profiles, no change, I've asked them to clear cache.  Waiting for confirmation on that.