I have Ubuntu 10.04 OS and a virtualbox (not the OSE) with windows XP as a guest.
When I choose Full screen in virtualbox the operating system (my guest, windows XP) is still in small screen.
I installed the guest additions. However, if I go to Devices on the Menu, it still shows "Install guest additions" like they were not installed. I can only choose 800x600 and 600x480 resolutions.
I'm using VB 3.2.8.
These are my settings:
General
Name: windowsxp
OS Type: Windows XP
System
Base Memory: 512 MB
Processor(s): 1
Boot Order: CD/DVD-ROM, Hard Disk
Display
Video Memory: 24 MB
3D Acceleration: Enabled
2D Video Acceleration: Enabled
Remote Display Server: Disabled
Storage
IDE Controller
IDE Primary Master: windowsxp.vdi (Normal, 10.00 GB)
IDE Secondary Master (CD/DVD): VBoxGuestAdditions.iso (32.01 MB)
Floppy Controller
Floppy Device 0:Empty
Audio
Host Driver: PulseAudio
Controller: ICH AC97
Network
Adapter 1: PCnet-FAST III (NAT)
Serial Ports Port 1: COM1, Disconnected
It looks like windows XP is using the VitrualBox Graphics Driver (Device manager > Display adapters : VirtualBox Graphics driver) It just doesn't show in full screen mode..