Open your terminal and type
sudo apt-get install v86d
Then
sudo -H gedit /etc/default/grub
Find this line
#GRUB_GFXMODE=640x480
and change for this one (of course choose your resolution)
GRUB_GFXMODE=1440x900
GRUB_GFXPAYLOAD_LINUX=keep
Note: You can try GRUB_GFXMODE=1440x900x24, but beware of specifying the color depth. You must specify a supported value. If does not work then rather delete it. More information in the manual.
Also note: older Nvidia graphics cards require the GRUB_GFXMODE property in the format <width>x<height>-<depth> (e.g. 1920x1200-24, but not 1920x1200x24).
Save file and type in terminal
echo FRAMEBUFFER=y | sudo tee /etc/initramfs-tools/conf.d/splash
sudo update-initramfs -u
sudo update-grub
It worked for me in all Ubuntu versions. Give it a try