Not repainting window properly

Hi, I’m using opengl mostly, then after a swapbuffers, I do a bit of CDC stuff (MFC). Problem is that the CDC stuff is not redrawn when I slide the window off, then onto the main MDI frame. Also, the startup splash screen has a similar effect on the CDC things. Any help appreciated.

Does it look anything like these?

as I have a similar problem, after some processing and a glutPostRedisplay the rendering in the scene goes funny! Any ideas?