Eu tive o mesmo problema e encontrei a solução aqui: link
Você precisa criar o arquivo /usr/share/X11/xorg.conf.d/60-teamviewer-fix.conf
contents:
Section "Monitor"
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "Monitor Model"
HorizSync 20.0 - 50.0
VertRefresh 40.0 - 80.0
Option "DPMS"
EndSection
Section "Device"
Identifier "Card0"
Driver "vesa"
VendorName "KVM - std"
BoardName "GD 5446"
BusID "PCI:0:2:0"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "Monitor0"
SubSection "Display"
Viewport 0 0
Modes "1600x1200"
EndSubSection
EndSection
Depois disso, reinicie seu servidor Ubuntu e o problema será resolvido.