this is what''s wrong: say I start in non-fullscreen mode: I see a tri. and a quad., fine! if I press F1 to go to fullscreen mode, the resolution is all messed up...the tri. and quad. become very large and over lap each other....(as if the picture is too big to fit on the screen and it cut in half, then superimposed)...and you see clear lines in the polygones. if I start in full-screen mode: both polygone display properly, then press F1, and I got a window...with tri. and quad., then another tri. another quad. as if the screen became smaller than the window and it cascaded... I am running it one a pretty crapy video card, it''s a 400Mhz machine with I think an ATI 3DRage Pro 32mb...(I hope this won''t happen in my gforce3 machine)... any hint??

well the rage pro has a crappy opengl icd. fortunatly for you however, you dont have a rage pro (the only came with 4,6 or 8meg of memory). you more likly have a rage fury which has MUCH better opengl support. more then likly you have a bug in your code. do the unmodified programs on nehes site exhibit the same problem? if so then more then likly you just need to upgrade your graphics drivers (you do have the latest?). you must realize that you have to reinit opengl (well at least reinit the rendering dc). you AMY just need to change your viewport settings to match the resolution. please actually get the proper information about your hardware next.

Well, I am running the code unmodifyed...and I do think I have the latest driver...and about viewport...no idea

and I don''t understand what do u mean by reini the DC...
in CreateWindow of lesson1 (which is run when switch b/t modes), it has a like hDC = GetDC(hWnd); ...is that it? or something else?