The Windows Client can't access the application data

Hi

We having a randomly problem with some users in a installation of Dynamics NAV 2013. The installation is running on Citrix and is installed in a VM Ware environment.

The problem occurs randomly as the user tries to open the Windows Client from the Citrix interface. The application starts but when it shall connect and pick up data to the client it suddenly “hang up” and the client is just empty (White)…

We have looked in to Logs etc but we can´t find anything. So what I would like to know if we can get som tips about where to start looking?

/ Daniel