Windows 7 - GTA IV Error

Hi there! My first post here. I seem to be having trouble launching GTA IV in 7 Home Premium from Steam. I get "Fatal Error: RMN20 - Windows Vista: Need to have Service Pack 1 or higher to proceed."

Now I have read other posts on here regarding the same problem on Win 7 Beta once the game was first installed. My problem is I have been playing this game fine for over 2 weeks. Last time was yesterday and now all of a sudden I'm faced with this issue.

Just wanted to see if anybody could shed some light on this as I've been unable to find any information regarding games that where working fine.

Any help is appreciated.

Thanks.

I have GTA4 running on my system fine youe should try updating everything first,
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GTA IV - 1.0.4.0 Patch (1.4), Grand Theft Auto Downloads, Grand Theft Auto Patches
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Reinstalled the game and changed compatability on the RGSC Launcher and GATIV exe to run on Vista SP 2 and it runs. Steam wont launch it though. Has to be done manually from the RGSC Launcher. It will have to do though.