Lenovo T61 using ext. display but awakens using laptop screen

[Muse]

I have my Windows 7 64 bit T61 connected by VGA to a 23" display, I switch to the external monitor from the laptop screen, choose the native res of the ext display, 1920x1080, fine. I put the machine in suspend but when awakened it's using the laptop's display again. To get the external screen instead of the laptop's screen, I have to change displays, then change the resolution from the laptop's to the external display's, a lengthy process. I can't see a way out of this, have tried everything I can think of/see. I even tried disabling the laptop's display, but it had no effect. What to do?