This is a known issue with some Windows graphics drivers, especially nVidia.
Your graphics driver does not support some of the features of OpenGL 1.1 that are required to run Cobalt v7 and older. Please contact your GPU or PC supplier to see if they have an appropriate driver for OpenGL 1.1 applications.
Some users have reported that they corrected this by switching Cobalt v7 over to using the Intel integrated graphics (may be called "Power Saving"), as this uses a different graphics driver.
Cobalt v8 uses the much more modern OpenGL 3.x, and so does not suffer these graphics driver limitations. - However this does mean v8 cannot run on Windows XP.
