There is a issue affecting mac servers tracked in https://www.nomachine.com/TR11L04663. This should be the problem reported by the original poster. A fix will be made available in the upcoming software update.
The problem on the linux server could be different. Does it occur only with Chrome or with any application?
@hoschi, we are unable to reproduce this problem on Chrome with the latest version of NoMachine. Can you update to 4.4.6 and let us know if you continue to have problems. A new thread can be started in the Linux section if necessary.
Can you open a new topic stating all the details of the issue, the browser type and version and steps to reproduce? I take it you are using 4.5 on both client and server sides. Make sure you state this in your new topic. I will be closing this thread, so we can start afresh. We will need the answers to these questions:
The NoMachine products and versions in use on client and server.
Operating system and desktop environment in use on client and server.
If server is Linux: are you connecting to a physical or a virtual display?
Can you provide specific instructions to reproduce the issue?