KDE4 crashes in 5.6

[Federico Giannici]

Hi!
I'd like to know if I'm the only one that have experiences crashes with 
KDE4 under 5.6-release amd64.

Often, during the startup or shutdown of KDE4, the bug report window 
appears saying that "Plasma Desktop Shell closed unexpectedly" 
(Executable "plasma-desktop", Signal "Segmentation fault(11)").

Moreover, once every 3-4 times the startup of KDE get stuck after the 
final big KDE logo appears in the startup page (maybe this is related to 
the first problem).

It happens in both my PCs where I installed KDE. I'd like to know if 
this happens only to me (to my hardware/software configuration), or is a 
common and known problem (and if there is any solution).

Thanks.