How did you resolve the desktop? If you installed EnvyNG, it would have automatically reconfigured your xorg.conf file for the correct resolutions. However, look in your /etc/X11/xorg.conf file for an entry that looks similar to this:
Viewport 0 0
You file may look different in that it may have a list of available resolutions. At boot up, the login screen reads the first resolution in the list and uses that. Check to see what it is set to and change it to the same resolution as your desktop. Make a backup of this file BEFORE you change anything. If you mess anything up, X will not start, so you would have to use the backup file by renaming it back to xorg.conf.