After some more tries with my setup (better and better but not till to a positiv end) I found an international download version including German language - and tested it. Surprisingly everything worked fine!!!!!!!!!!
So I come to the conclusion that some files on my DVD from US are corrupt in a way the operating system cannot find it. Clear it's remarkable that an official software DVD can have these mistakes, but no doubt.
Now I've to find out a way to come from a working "testversion" to a legal status.