Problem solved. I use x-mouse, so that windows focus is activated on mouse over. Unfortunately this appears to fight with certain OpenGL games, Multiwinia/Defcon/Half-Life 1 in OpenGL Mode. This looks to be a either a Microsoft bug or a nVidia driver error. Solution: Disable X-Mouse =) Great game gu...

The problem persists with the 175.19s drivers

I forgot to mention that my 8800gtxs are in sli, if that makes any difference. I've disabled sli in every way I know possible, bar taking out a card, and multiwinia still flickers.

Sorry, didn't spot the drivers in your post. However, quoting IRC: <%KingAl> Jelco, that bloke reports having driver 177.86, but... popping over to the Nvidia site and searching for the latest 8 series Vista 64 driver gives me - 175.19 ? I imagine you do have a beta version installed at the moment,...

Drivers are the latest ones released by nvidia, that aren't a dodgy beta.

Solution: Disable X-Mouse. If I run Multiwinia in fullscreen mode, on mouse click, the whole screen will flicker and the mouse click will sometimes not register ingame :(. Obviously, with a lot of clicking, the game turns into an epileptics nightmare. Any suggestions? Vista 64 sp1 8800gtx 177.83s Lo...