Are you using ubuntu as Guest OS. I managed to have the screen resolution (auto resize) worked when working with ubuntu version up to intrepid (8.10).
Firstly, you should install guest addition. Just log in to ubuntu and from the virtual box menu (press host key to access it) go to Devices --> Install Guest Additions
Open your CDrom Drive in the Guest OS.. Open the drive folder and drag VBoxLinuxAdditions-x86.run to your desktop.
Open your terminal and direct it to the desktop and invoke the following command.
sudo ./VBoxLinuxAdditions-x86.run
Enter your root pasword and you will be done.
Final step just requires you to restart the virtual machine and the screen size will be adjusted accordingly. You now can use the seamless mode which is great in my opinion.
Edit: okay
Start up your Ubuntu VM and mount the VBoxGuestAdditions.iso as a CDROM (it should be in the VirtualBox program folder). Open a terminal and change to the CDROM (on my system it was /media/cdrom0) and use sudo to execute VBoxLinuxAdditions.run.
For the technically uninclined, open the terminal (Applications > Accessories > Terminal) and type the following (case sensitive!):
Code:
cd /media/cdrom0/
sudo ./VBoxLinuxAdditions.run
After it finishes it will tell you to restart. Restart Ubuntu and when it comes up again, you'll have full resolution control. To change your VM resolution, just resize the VirtualBox window and Ubuntu will automatically adjust to it! The screen resolution control panel will also have 1280x800, 1280x768, and 1024x768 available as standard resolutions (on top of 800x600 and 640x480 of course).
Edit:
I'l give you 2 more Tipps!!
Start up your Ubuntu 8.04 guest. In VirtualBox, click Devices->Install Guest Additions and your virtual Ubuntu should recognize a new CD. Open a terminal and run this command:
sudo /media/cdrom/VBoxLinuxAdditions.run
The installer should prompt you that it’s time to restart the virtual machine once it’s done. Just logging out and back in should work.
This is where things get sticky. For Ubuntu 8.04 guests, the VirtualBox video driver will not be enabled because of the minimalistic xorg.conf file.
Open your guest machine’s xorg.conf file:
gksu gedit /etc/X11/xorg.conf
Find the device section, which should look like this:
Section "Device"
Identifier "Configured Video Device"
EndSection
And replace it with this to enable the VirtualBox driver:
Section "Device"
Identifier "Configured Video Device"
Driver "vboxvideo"
EndSection
Changing screen resolutions in Ubuntu 8.04 is done with RandR, which is not supported by VirtualBox. So you’ll also need to set a resolution manually. Find the screen section, which should look like this:
Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
EndSection
And replace it with this, but change 1024×768 to your preferred resolution:
Section "Screen"
Identifier "Default Screen"
Device "VirtualBox graphics card"
Monitor "Generic Monitor"
DefaultDepth 24
SubSection "Display"
Depth 24
Modes "1024x768"
EndSubSection
EndSection
Save, exit the editor, and log out. You should now have a large virtual machine window, as well as mouse pointer integration.
This is 2nd tipp!!
System set-up:
Host: Ubuntu Studio 8.04 AMD 64 (Hardy)
Guest: Ubuntu 8.04 x86 (Hardy) - I was not able to run AMD64 versions of Ubuntu as the guest system.
First, setting up the host system:
1. Before starting, it is always a good idea to download and install all updates from the repositories, including kernel updates. Especially so in this case since we will be compiling kernel modules and this can save you the the work of recompiling again when Ubuntu releases a new kernel version.
2. After updating, restart your computer to load the new kernel, if any.
3. Install the kernel source and some other tools. This is needed because VirtualBox will be compiling kernel modules:
sudo apt-get -s install build-essential linux-headers-`uname -r`
4. Download VirtualBox 1.6.2 binary version (not open source edition) from http://www.virtualbox.org/wiki/Downloads. I selected the Ubuntu 8.04 AMD 64 version.
5. Install VirtualBox by double-clicking on the icon of the downloaded file.
6. Add users that will be using VirtualBox to the group vboxusers.
7. Do a small fix a needed in Ubuntu to make USB work properly and to prevent an error message from appearing when entering settings for USB in VirtualBox. This is explained in the VirtualBox FAQ. What you have to do is edit the script `/etc/init.d/mountdevsubfs.sh and uncomment the four lines around line 40 (Magic to make /proc/bus/usb work). Then execute
sudo /etc/init.d/mountdevsubfs.sh start
Then, setting up the guest system:
1. Start VirtualBox on the host and install the guest OS from an ISO-file og CD.
2. I got a kernel panic when trying to install the guest system. The solution that worked for me was to enable ACPI, IO APIC, VT-x/AMD-V and PAE/NX in settings - general - advanced in VirtualBox, but I am not sure what actually made the magic...
3. Install all updates from the repositories, including kernel updates.
4. Restart the guest OS
5. Install some special drivers to get smoother screen, keyboard and mouse performance: When the guest OS is running, select "Install guest additions" from the Devices menu of VirtualBox. A virtual CD is mounted on your system with the files needed. Start a terminal and do
cd /media/cdrom
sudo bash ./VBoxLinuxAddition.run
Then restart your system and when you log in you should have a full resolution.
Good luck!
Let me know if you still have problems after trying those tipps!!