I have tried all alternatives and resources that I found on internet to achieve to change screen resolution in my MacOS X guest. I have the latest VirtualBox version (4.1.22) and I have MacOS X 10.6.3 Snow Leopard running in a vm guest. Some solutions that don't work for me are: Tuning virtual machine settings: Adding and in the .vbox file, or running these two commands: vboxmanage setextradata "MAC OS X" "CustomVideoMode1" "1360x768x32" vboxmanage setextradata "MAC OS X" "GUI/CustomVideoMode1" "1360x768x32" Editing Guest OS boot configuration: Modify /Library/Preferences/SystemConfiguration/com.apple.boot.plist with these lines: <key>Kernel Flags</key> <string>"Graphics Mode"="1360x768x32"</string> <key>Graphics Mode</key> <string>1360x768x32</string> Any other suggestion, something that I was missing. Thanks in advance,