Hi,
i solved the problem, but i still don’t know what was going on. The solution was to make a x86 build out of Unity 5 and copy the right 32bit Tobii.EyeX.Client.dll manually in its root folder (overwriting the wrong placed 64bit dll). The reason why the former x86_64 build did run on both of my machines (Desktop & Laptop, Win 7 Ultimate) and suddenly stopped working on the Laptop is still unknown to me. Maybe, when i have some more time, i’ll look into it again and i’ll try to reproduce the problem.