It's possible it's set for the external to be the primary in the BIOS.
I have a Toshiba Satellite P100 that is about 3 1/2 years old running Windows XP. I have noticed a strange problem recently. When I start up my computer the screen is black for the Toshiba and Windows splash screens but once it finishes starting up I can see the Windows Login screen just fine. Everything else on the computer is running perfectly but I am concerned this is an indication of an unseen problem to come/ a virus of some sort. I tried to get into my BIOs but I can't because the screen remains black when I hold down the key. Any advice or information that anyone can assist me with would be greatly appreciated.