There where two addtional freezes caused by firefox on other webpages
like windy.com.
It seems that webpages with intense graphics can cause the system freeze.
But there are two other events where the system freezes obvious in other
applications.
In many cases the process plasmashell is going into 100% cpu usage, so I
will try to move this bug to KDE.
Attached is an screenshot of the system in freezing KDE state, made by
logging in from another PC via ssh.
As already described the KDE is absolutely dead and only reset of the PC
helps.
