We started having the same issue today and even with the vpshere Thin client we would get the same error message. I believe it is issues with our antivirus program, and found false positives that must of started recently. Here is what I found (see the link below). While this is not a solution, it is a workaround I am using for right (disabling antivirus) so that I can launch the client. Not recommended or ideal, but nothing else I tried work.