Hi, before I had a problem with gta IV on my windows 7 64bit, not ran me, well, today I found the solution:
The file "LaunchGTAIV.exe" right click - properties - compatibility - and check compatibility with Windows XP SP3.
Having done that, if you still gives the problem, you need to download and install this patch (1.0.1.0):
http://files.rockstarwatch.net/patches/GTAIV_PC_Patch_1.0.1.0.exe
So simple, when you have installed the patch run the game and I worked, I worked me 100%, I hope that you too.
regards
PD: SE which is a very poor post, but this solution is not needed anymore!
They can check in comments that really works.
A greeting!