My specs:
Vista Enterprise
Intel Core Duo 3,16Ghz with 4GB Ram
8800GT with 512MB DDR3
DirectX 10
FFH2 version 31e
With the prior version (d) I had the same issue . . . Basically the game runs fine, but at some point in late game I have a CtD (between turn 450 to 525) . . . Since I play on Huge maps, usually Terran (supposedly making them even larger), I figure it's a performance issue, though since I only just bought my PC I would've thought it could handle it . . .
I've recently started a game on a large map, hoping this will help - I figure there's no need to install DirectX 9.0c as well, after the new e patch for FH2 has come out . . .
EDIT: Since the large map didn't seem to pose a problem (albeit I never actually finished that game), I opted to try out another Huge one with all factions involved . . . Have yet to see how that'll turn out . . .