Stuck on turn 332

[Tarostar]

Playing on the largest earth map hitting Next Turn no longer works on turn 332. I can still move around the map and give orders, but I cannot progress. Turning on Auto Turn made no difference.

This is after being forced to use DX9 with medium graphic settings and lower than usual resolution (DX10/DX11 causes frequent crashes and blue screen with error code 0x00000050) despite having an ATI 5770 graphic card and quad cpu Phenom II with 4 gig ram.

I've kept playing despite computer turns taking 20-30 seconds to resolve later in the game, frequent freezes as it decides which unit is next, weird red splotches on the map and moving around the map causes slow redraws of grey tiles.

I've been trying to play this game since Friday. Tweaking settings, updating drivers and reading forums - but as it is now this game is not playable. Very disappointed to have been so punished for being an early adopter.

When it works Civ V is lush to look at and fun to play, sadly the crashes and slow resolution of computer players take the fun out of it and I'm giving up now.