i have windows 7 and i cant run gta 4 ( error dd3d30). i have the system requirements. I tried changing the compatibility to win xp, vista, etc...
Have you tried google? I searched for dd3d30 and it came up with: 'Results 1 - 10 of about 39,500 for dd3d30' Note the 39,500 part, I'm sure there is a solution somewhere in that lot! I apologise if you have already searched for the answer!
What graphics card do you have? Do you have the newest drivers for it? Are you running the newest DirectX binaries? If youre under Vista or Windows 7, did you install the DX9 binaries? Are you running the newest version of GTA IV? Does it have any patches at all? Your question right now is in line with asking: "Hi, my car stopped, can you please tell me why?". We need a bit more details.
What graphics card do you have? GTA 4 has trouble recognizing some's memory and sometimes won't start unless you use a certain commandline.txt file
I am using 9400GT graphics card that is working well so I think you should use this one then to play GTA 4 your minimum requirement is, Windows OS, Intel core 2 Duo 1.8 HGz processor or AMD Athlon X2 64 2.4GHz, 1.5 GB vista or 1 GB XP memory, 256MB Nvidia 7900 graphics, DirectX 9.0c Compliant Card, minimum 16 GB Hard Drive Space and 5.1 audio card.