Virtualbox 4.2.10 Auto resize not working. Will auto-resize down but not up unless in full screen

From the virtualbox.org manual Chapter 9. Advanced topics :

When guest systems with the Guest Additions installed are started using the graphical frontend (the normal VirtualBox application), they will not be allowed to use screen resolutions greater than the host's screen size unless the user manually resizes them by dragging the window, switching to full screen or seamless mode or sending a video mode hint using VBoxManage. This behavior is what most users will want, but if you have different needs, it is possible to change it by issuing one of the following commands from the command line:

VBoxManage setextradata global GUI/MaxGuestResolution any

will remove all limits on guest resolutions.

VBoxManage setextradata global GUI/MaxGuestResolution >width,height<

manually specifies a maximum resolution.

VBoxManage setextradata global GUI/MaxGuestResolution auto

restores the default settings. Note that these settings apply globally to all guest systems, not just to a single machine.

In the case of the poster, it was the first command that fixed the problem.

FIX: Oracle VM VirtualBox Manager -> File -> Preferences -> Display -> Maximum Guest Screen Size -> Automatic