Each time I try to launch Modern Warfare 2, I'm getting this error message:
"Please make sure Modern Warfare 2 is run from the correct folder "
- In Steam: Right-click the single player mode or multiplayer mode of Call of Duty then go to Properties> Local Files> Verify the entire cache of the game ..
- Steam will check if any files is missing and download them.
Thanks to Nubkratos for this tip.