Hey Freemangordon and Estel! Many thanks. I installed CSSU-thumb last night again. In the morning my N900 desktop freezes and after a reboot I found a new message. Then I ran apt-get update / upgrade. And one thing has been installed (I have forgotten, what exactely, something with "i..." or "l...") and since now the problem is away. The N900 seems to work without problem till now. But I would to be prepared: Where do I get the app "syslogd". I cannot find it in the Application Manager?