'SecuLauncher: failed to start application. [2000]' .. HOW TO SOLVE

Please note that this is a common , SIMPLE  issue when the Visual Studio C++ redistributable and/or Microsoft .NET Framework 3.5 was not installed properly.
  
dont reinstall your game .
JUST FOLLOW THE  STEPS GIVEN BELOW 

 1 . INSERT your
'Grand Theft Auto IV' Disc #1 into CD/DVD drive .

2.  DON'T LAUNCH THE CD SETUP . right click on dvd drive and click explore or open it to view or see files in the dvd .

3. LOCATE THE FOLDER  'REDISTRIBUTABE' in the disk.

4.  In that folder you will find a file called 'vcredist_x86.exe'. open it and follow the installation wizard instructions . 

5. after its installation , Please also download and install the latest version of Microsoft .NET Framework 3.5.
  
important note : GTA 4 IS MUCH LARGER IN SIZE . So check if there is minimum space (memory) on local disk C : to install microsoft .net framework 3.5 and C++ (vcredist_x86.exe setup ).


after installing  it successfully , please restart your computer .
 IF gta 4 launches successfully CONGRATS TO YOU !!!! 

OTHERWISE comment in given below box , what your next problem is ... 
Dont forget to see lots of videos on Youtube for this problem.
try installing FADORS's crack file or razor's crack file . bust ask me before it . 
THANKS !!