After the installer told me to connect it, I do so. I've downloaded the driver from saitek, and started it with a disconnected X52. So I hope anyone out there had the same problem and found a way to fix it:
The guy from MadCatz support said, because the X52 works on my old system, they can't help me. I used this stick on my old rig, and after some research I finally found a way to install this weird software successful, but all those hints didn't work on my new rig. I'm sorry to ask so many questions, but I tried a lot to install my Saitek X52 Pro again, but without success