I could try your code on my machine and see what I get if you would like. And I could take a look at your code too if you wanted.

Any DirectXperts out there know what could cause a DX backbuffer surface to be filled with garbage? This whole problem started when I downloaded Nvidia's latest Riva TNT reference drivers (Detenator 3.53 if I remember correctly). After that none of my compiled code worked. I kept getting the DDERR_SURFACELOST return when trying to lock the backbuffer. Restoring didn't help either. I have since went to the extreme of formatting the harddrive and reinstalling Windows 95 with the factory drivers for my Creative Graphics Blaster 16MB Riva TNT card. Now the surface locks fine but when I call flip from the primary, I get a screen full of junk. Kind of reminds me of DOS when forgetting to clear video memory out.

I have pored through my code again and again. I have compiled other code samples and they work just fine. So that tells me it's a problem with my code, which worked fine before I ever downloaded those drivers. This whole mess has got me banging my head against the wall (it's either that or my monitor).
Replacing the calls to the back buffer with the primary surface displays just fine. Only the backbuffer is grabled.

I've ruled out the factory drivers because the code I compiled from other people (books, net) worked fine. I've cut and pastted into my code and it still didn't work! All the commercial products I have that use DX work fine as well. Any one have any ideas as to what could cause this? I'm using DX 7 BTW.