We will have to edit grub configuration. Open a terminal and paste this:
sudo gedit /etc/default/grub Hit Enter. It will open grub preferences in Gedit.
Locate the line # GRUB_GFXMODE=800x600 (resolution may be different).
You have to change the resolution to actual resolution of your screen, for example mine is 1240x1024. Next step is to uncomment this line (remove the # and and the empty space if is, so the letter G of the word GRUB will be the first letter in this line). After you are done, save the file and close.
3 . Now paste this line in terminal:
sudo gedit /etc/grub.d/00_header .
Hit Enter. It will open a text file with a lot of stuff. Use the search option at the top of the window to locate this line:
gfxmode=${GRUB_GFXMODE}
After you successfully find it, you will have to add this line: set gfxpayload=keep just under the gfxmode=${GRUB_GFXMODE}. Make it look like this:
set gfxmode=${GRUB_GFXMODE}
set gfxpayload=keep
Now, save the file and close.
4 . In terminal paste:
sudo update-grub
解决Vmware中安装Ubuntu Server 14.04 分辨率无法全屏问题
原文：http://my.oschina.net/mayboy24/blog/316407