hi, thanks for Answer,but after a few Weeks i reported this Bug, i have noted that the Disk, on that the System was installed, had many Errors and i had often to reinstall some Software that become corrupt without any Reason.
I have changed the Disk, reinstall the System and now it's running well. I think it was that Hardware-Error that corrupt apt. Now all works fine. Gerrit Addiks (sorry for bad English)