Multiple AutoCAD LT 2008 Windows

Our drafting manager reported that his AutoCAD LT 2008 no longer opens multiple Windows. He said used to be able to click on single drawings and it open an AutoCAD session and if he did another one, it would open another session. He also says he used to be able to multi-select drawings when opening drawings within AutoCAD and that no logner works.

Now, it just opens one drawing and if he tries to open another, it will attempt to save the drawing open and then close it when he opens the new one.

He needs to restore the ability to open multiple drawings. I did try the command set sdi 1 and it had no effect.

Suggestions? Thanks!