I'm having same kind of problems with MSI P43T-C51 and a Geforce 9500GS. It either freezes the whole computer or freezes the display, depending of driver version. When connecting remotely, the desktop size is 0x0 pixels. Without drivers the card works in VGA compatibility mode OK, but when drivers are loaded the symptoms appear.
The 9500GS is working OK on another board, so I must beleive it is a BIOS issue with this motherboard.
As the others say, it has nothing to do with DDR3 memory on graphics card as I have another HD4670 with DDR3 and it works superb! Has to be an issue with nVidia cards and this motherboard.
Tried a Geforce 6200TC and works nice too, but not with 9500GS.