broken colour buffer

I’m drawing to 3 different areas within a window using glScissor.
the images draw OK, but the colour in two of the areas is all messed up: i’m getting an ugly beige colour drawn over the images.

One of the areas is acting as a test routine: i clear the colour buffer then use glutBitmapCharacter to write some text to the screen. the colour for the text is set the same as the clear colour, so the text should be invisible, but instead it’s beige. not good!

in the subroutine, the functions i call are:

glClearColor(1, 1, 0, 1), (yellow)
glClear( color buffer bit and depth buffer bit),
glColor4f(1, 1, 0, 1),

Has anyone any idea how to fix this, 'cos it’s driving me mad, and that’s not a good way to be on a friday!