Desktop doesn't come up

[virtual-lab]

Hi there,
I recently moved two Windows machines from a Linux host to another, respectively a Windows server 2003 and Windows server 2008. Both have same configurations except for hard disk images and UUID.
The 2008 works fine, while on the 2003 I have some trouble with the desktop, I can successfully boot and next login, but desktop stuff doesn't come up. I can open the task manager, from which I can see the process explorer.exe is running and always trough the task manager I can also open new tasks such EventViewer (no errors related) and DOS. But I cannot see the Start bar or any icons, just a grey screen.

Machines run as no root user with the following command

sudo -H -u vbox VBoxManage startvm ithaca --type vrdp

I am accessing them directly from the host machine, a RedHat 5.3 using the following command

rdesktop -a 16 localhost:3390

which it opens a quite big window and saying:
WARNING: screen size changed from 800X600 to 1088X710


BTW
I've spent the all day trying to resize that window, but with no luck. So please avoid to mention any reference to documentation because I've already gone trough it and nothing changed.

VBox.log is ok, no errors.

I am considering something related to guest additions, but since I don't know how to access Computer resources without the desktop environment I cannot make any upgrade.


Any help is welcomed.

Thanks in advance
Regards

Alessandro Ilardo