The frontend of Linux is running on the same host where the Gsx Server ist installed.
Now the problem, if you´re open the frontend of Linux and grab one virtual machiene and now you kill the whole x session, ALL virtual machines suddenly powered off and they
are in powered off mode 
They don´t shutdown correctly, just like a reset(hard poweroff)!
This happens also if a normal user is using the frontend, this caused not by user root i.e.
Thanks very much to find out what happens here !!