Toshiba Equium L20 - Manual (Page 153)

User’s Manual B-9
Display Controller and Modes
5. When the LCD (internal liquid crystal display) display mode is selected,
the Virtual (Virtual Screen) display mode can be set. However,
afterwards, it may not possible to change the screen resolution to more
than 1280 x 1024 pixels in Highest (32bit) mode (for example, when you
attempt to set the resolution to 1600 x 1200 using the Screen resolution
slide bar and then select Highest (32bit) mode from the Color quality
drop-down menu).
In these cases, perform the steps below:
First, use the Screen resolution slide bar to select the 1024 x 768
resolution, and then change the resolution to more than 1280 x 1024
and select Highest (32bit) from the Color quality drop-down menu.