MAXScript remembers the state of its desktop (the location of active Editor and Listener windows) when you exit 3ds Max and restores this state when you restart MAXScript. Any Scripting Editor files missing when you restart will not have their tabs reopened.
The desktop state is stored in a file called maxscrpt.dsk in the user's local profile folder of 3ds Max. You can query the location of the path by calling getDir #maxData in the Scripting Listener.
On Windows 7, it typically looks like
C:\Users\YourUserName\AppData\Local\Autodesk\3dsMax\2012 - 64bit\enu\
and reflects the 3ds Max version and build (32/64 bit).
You can rename this file and replace it if you want to keep several desktop setups configured, or simply delete it so the current desktop will not be restored.