The same problem continues now for two more days. It seems, that the avast program wants the my PC 20 minutes every day after start up. The process is called AvastSvc.exe described as avast! Service. I have discovered the following during these 20 minutes:
1) If I restart the PC while this process is active, the problem continues after this again.
2) If I restart the PC after this process has finished, the PC will not be occupied by this avast process. So it seems like it is only once within a 24 hour period
3) I can start the MS browser during this - its actually the one I use now while this do happen
4) There seems to be some small constant network activity. The CPU is used 100 %
5) I cannot start the Avast UI. However aften the 20 period the Avast UI will open.
6) All other PC programs runs very slow.
Please help