Find toshiba.com-->download

Usually the driver is supported by the manufacture. However, I can't locate Dynabook. Is it bought in the US? If it is not sold in the US, maybe you need to visit toshiba.com.jp or alike.

Almost all major manufactures will have something called "download" or "support" where you could locate drivers.

1920x1200 is not very big, and if you laptop is less than 5 years old, it should be able to support with enough video memory. It should be a driver thing.