@DavidR
Thanks David, just found the Problem by myself. Not the Mail Provider had the problem, but the WEB Provider. I know now, this error happened for following reason:
I had deinstalled AVAST with their tool "aswclear.exe " but this tool did not remove the installation path for the ashwebsv in the registry. I later reinstalled avast but into another directory. The registry still showed for ashwebsv the older path from previous install. No wonder he could not find the file ....
Thanks
Ulrich