Second Monitor Blacks after Unlock

I have a fujitsu t-series laptop running 32bit Enterprise. I use an Acer x163w for an external monitor. When the monitor is connect and the computer starts up, after I log in, both displays work fine for about 4 seconds then both go black and only the laptop display returns. The same behavior happens when I unlock my computer: both work for about 4 seconds, both go black, and only the laptop display returns (the Acer remains black). To fix this I have to do one of two things: 1 unplug and replug the vga cable from the back of the comp, or 2: reset my display settings to extend the display to the second monitor. I have searched google for a solution but I havn't found anyone describing the same problem. Any Ideas?

I intend to use the second monitor to extend the desktop. I think the key combo you are reffering to (fn+f10) only alternates between the two monitors, an exteded display is not one of these options

im not entirely sure what a mobility gpu is. In my device manager, Mobile Intel 4 Series Chipset Family is listed under Display Adapters. does that help?

any luck, its something i have temporarily fixed before. if i recall correctly it was an issue with which particular programs run at start up.