Only Brown Colours

When I run OpenGL in Dev C++ I get only shades of brown. This includes online samples, it is a recent development, they used to work fine, other code like SDL samples work fine, except if they include GL.h then I get only brown colours, even black is a reddish tinge. This includes both primitives and texture mapping.

What’s the platform? Could it be a pixel format problem?

Windows, I’m not familiar with pixel format.