Comment 7 for bug 1760068

Me too. Xubuntu 18.04, fresh install.

It happens after resume from suspend and when I switch users (dm-tool switch-to-greeter). For the first user the resolution is correct:

user_a$ inxi -G
Graphics: Card: NVIDIA GT215M [GeForce GT 335M]
           Display Server: x11 (X.Org 1.19.6 ) driver: nvidia Resolution: 1600x900@59.98hz
           OpenGL: renderer: GeForce GT 335M/PCIe/SSE2 version: 3.3.0 NVIDIA 340.106

user_a$ xrandr --query
Screen 0: minimum 8 x 8, current 1600 x 900, maximum 8192 x 8192
VGA-0 disconnected (normal left inverted right x axis y axis)
LVDS-0 connected 1600x900+0+0 (normal left inverted right x axis y axis) 345mm x 194mm
   1600x900 59.98*+
HDMI-0 disconnected (normal left inverted right x axis y axis)

But for the second user:

user_b$ inxi -G
Graphics: Card: NVIDIA GT215M [GeForce GT 335M]
           Display Server: x11 (X.Org 1.19.6 ) driver: nvidia
           Resolution: 640x480@73.00hz
           OpenGL: renderer: N/A version: N/A

user_b$ xrandr --query
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 640 x 480, current 640 x 480, maximum 640 x 480
default connected 640x480+0+0 0mm x 0mm
   640x480 73.00*

Note: user_b screen resolution is fine if he is the only one using the system. The problem happens only when he is the second.

Thanks.