Right! Solved the flickering shadows with Nvidia SLI 8800's :(
 

Why the sad face?

Well, I have no idea why it fixes it but it does!

Went into IL2Setup, and chose Windowed Mode, instead of full screen.

I have 2x8800GTS in SLI, Rendering Split Screen Mode, VSync off, 8xAA 8QxAF, and up until today have been watching planes crash into the sea, and then watching as the shadows flash on and off, and I've been pulling my hair out!

Anyway, chatting with a friend of mine (Scragbat) he said to try switching the game to Windowed mode and seeing if it makes a difference as he always plays it Windowed and never gets that 'flicker' effect.

So I went to IL2Setup.exe, changed it to 1152x864, launched it...and.......no flicker!

Went back to full-screen, flicker comes back!

So, is there anyway of changing the resolutions in Windowed Mode to allow 1680x1050 and 1920x1200.

Windowed mode cures it for me....no idea why.

Any offers!

Cheers, MP.