Shutdown not working on Fedora 31 with XFCE

[Meikel]

Hi folks,

when I shutdown my Fedora 31 XFCE via the menu, the system goes down, 
and then after one or two seconds automatically restarts.

What I' ve to do as a work-around to shut the system down is to log into 
a console and type "sudo halt" which halts the system. When a message 
indicates that the system is halted I then power the machine off.

Any ideas why a shutdown via menu doesn' t work?

Regards,

Meikel