If you are currently running Vista or Windows 7, please complete the instructions in the following link:

• Windows 7 and Vista Troubleshooting

If you are running in Windows XP, take the following steps:
1) Exit Steam.
2) Go to the "Start" menu, select "Run", type "regedit" and click "OK".
3) Navigate to the following registry key: HKEY_CURRENT_USER\SOFTWARE\VALVE
4) Right click and select "Permissions"
5) Check the "Allow" boxes for "Admin" and "System" for both "Full control" and "Read".

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The remaining steps apply to *all* versions of Windows.

Please verify the GCF for this game as outlined here:

• Verifying Game Cache Files (GCF)

Note: Files may fail to verify. This is normal and can be ignored.

Then test the issue.

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If you still have difficulty, you may also need to manually run secondary installers required by this game.

Exit Steam entirely.

Browse to your Call of Duty: Modern Warfare 3 installation folder (Usually C:\Program files\Steam\Steamapps\common\call of duty modern warfare 3\)

Run the following installers:

...\Steamapps\common\call of duty modern warfare 3\redist\directx\dxsetup.exe
...\Steamapps\common\call of duty modern warfare 3\vcredist_x86.exe

Reboot your computer and test the issue again.

If the issues persist, please complete these guides:

• This game is currently unavailable
  
• Games do not run after 'Preparing to Launch'

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Further support for this title is handled by a third party support department - please follow the instructions below to contact the support provider to troubleshoot this issue:

• Call of Duty: Modern Warfare 3