We just learned that Pandoras Box Version 4.5 has a problem to create Tumbnails on Server Clients in some situations.
If you experience such a problem check your NVIDIA Driver Version.
If it is lower than 185.85 please update to 185.85
You can download the driver in our download section.
viewtopic.php?f=83&t=516
!!Important: Do not update to any NVIDIA Version 190.xx.!!