Now that the error message was kind of fixed by myself, I tried to install the beta2 again.
Here is what happend then:
The Jupiter-8V 2.0.2 as well as the Jupiter-8V 2.5 beta2 were registered in software (control panel) on my system. I saw this after I had to experience what you can see on the snapshot attached. Well, I uninstalled both versions, reinstalled the beta2 and guess what happend? Nothing! All I was getting is the same as what you can see on the snapshot attached. Great!

Now, I've still no answer to my request and the fact that all the other updated (2.5.1) V Collection 2 synths are not running on my system, is really making me lose trust in Arturias work.

Will the V Collection 2 and the Laboratory ever run on XP, or should I give up and maybe sell them because I can't use them? What a pitty !!!
I would be massively thankful for any advices or tips
here!!! Seams like I'm the only one stupid enough, to still use XP. But if XP would support more RAM and multi-core processors I would never ever switch to Windows 7!