GTA IV Fatal Error: RMN40?

I bought GTA 4 from Steam a little while ago, and now all of a sudden when i go to play it, this error pops up stating i need to have service pack 3 or higher to proceed. The weird part is that i have downloaded this service pack and yet this error still pops up. When i proceed to try to run LaunchGTA in compatibility mode using Windows Xp service pack 3, i receive the same message as though it ignores the fact i am already using service pack 3. My computer is running Windows 7, which is why all of the solutions posted on the internet about this problem do not really help.