GTA IV Launch error on steam

[Picklelangelo]

I have experiencing this problem while trying to turn on my GTA IV, which I bought several days before on steam. The game launches, when I start it not from Steam, but from my games folder.

This is the error I get:

"GTA IV FATAL ERROR: Windows Vista: Need to have Service Pack 1 or higher to proceed."

And I do not know what to do, because my Windows 7 is a Service Pack 1 edition...

Any suggestions?

[Loot_Goblin]

If this error states a different version of Windows than you have installed, Steam or Grand Theft Auto IV are set to run in compatibility mode.
Please follow the instructions below to disable compatibility mode.
Close Steam by clicking the Steam menu, then selecting Exit.
Browse to your Steam installation (Located in C:\Program Files\Steam\ by default).
Right-click on Steam.exe (If 'exe' is not visible, look for the black and white Steam icon) and choose Properties.
Click on the Compatibility tab.
Uncheck any boxes that are checked and click Apply.
Repeat these steps with GTAIV.exe (located in \steamapps\common\grand theft auto iv\GTAIV\) for Grand Theft Auto IV or LaunchEFLC.exe (located in \steamapps\common\grand theft auto iv episodes from liberty city\EFLC\) for Episodes from Liberty City.
Click the Show settings for all users button, then uncheck any boxes that are checked and click Apply.
Click OK until all dialog boxes have been closed.
Re-launch Steam and re-test the issue.

once you get to the property stuff. make sure you do whats on the list but change the top from what ever it is to windows 7. To do so click on the bottom left button. and it will let you change it in the Steam client.