blank screen on switch user

Hey ,
New install of Mageia4
Nvidia Geforce 640 ( using propriety Geforce 400 or later driver ) .
So sometimes when I log out and log in with another user name the screen remains blank . I was going to try the xorg driver ,so I went to the set up graphical server and looked at the names under the xorg list ,there is no driver listed that looks obviously nvidia geforce specific .Which one should I use for a Nvidia geforce 640 ? .
Once I do have this blank screen I usually reset the comp . Not good has this has caused my system to be corrupted .Is there a safer method to reboot using just the keyboard that shuts down the system correctly .
Hope this can be resolved as I do want to keep mageia, but the blank screen issue means my system is not reliable .Hopefully the free driver will sort it out .
New install of Mageia4
Nvidia Geforce 640 ( using propriety Geforce 400 or later driver ) .
So sometimes when I log out and log in with another user name the screen remains blank . I was going to try the xorg driver ,so I went to the set up graphical server and looked at the names under the xorg list ,there is no driver listed that looks obviously nvidia geforce specific .Which one should I use for a Nvidia geforce 640 ? .
Once I do have this blank screen I usually reset the comp . Not good has this has caused my system to be corrupted .Is there a safer method to reboot using just the keyboard that shuts down the system correctly .
Hope this can be resolved as I do want to keep mageia, but the blank screen issue means my system is not reliable .Hopefully the free driver will sort it out .