In certain cases running a VirtualBox VM in a headless linux environment can lead to a Windows XP having an undesired resolution.
I fixed this using the following two commands:
VBoxManage setextradata global GUI/MaxGuestResolution 1920,1200
For a running VM:
VBoxManage controlvm "remote" setvideomodehint 1920 1200 24
I found the resolution in this forum: