We have experimented now with different way and have found a solution for us. Here is the situation and our working solution for this.
We have the problem we described in the posting before. We have checked tat we can back to the version before but no easy way exist without restore.
But we have downloaded from snowcovered the version DMX 03.04.08 for .Net 1 and installed this on our Portal. The result the DMX self working without any problem.
We are a little bit confused we work with DNN Version 04.03.06 on .Net Framework 2.0.507.27.42 also .Net 2 but the Net2 Version of DMX works not on our Net2 portal.
We are very interrest about the source of the problem!