Got this error today.. never seen before...
https://support.steampowered.com/kb_art ... -ILZV-2837
An issue with your computer is blocking the VAC system. You cannot play on secure servers.
How do I fix this?
Repair the Steam Service
This may also indicate a Steam Service failure. Please try repairing the Steam Service:
Exit Steam.
Click Start > Run (Windows Key + R)
Type the following command:
"C:\Program Files (x86)\Steam\bin\SteamService.exe" /repair
(If you have installed Steam to another path, please replace C:\Program Files (x86)\Steam with the correct path.)
This command requires administrator privileges and may take a few minutes.
Launch Steam and test the issue again.
Enable Kernel Integrity
Kernel Integrity checks must be enabled to play on VAC secured servers. To enable Kernel Integrity checks please follow the steps below:
Exit Steam.
Click the Start button, then 'All Programs', and 'Accessories'
Right-click on Command Prompt and click "Run as administrator..."
- Please note if you are running Windows 8 you will need to press Windows Key + X and select Command Prompt (Admin)
In the command prompt, type the following commands and press Enter after each command:
bcdedit /deletevalue nointegritychecks
bcdedit /deletevalue loadoptions
Restart your computer.
Launch Steam and test the issue again.
Turn off Kernel Debugging
Kernel Debugging must be turned off to play on VAC secured servers. To turn off Kernel Debugging please follow the steps below:
Exit Steam.
Click the Start button, then 'All Programs', and 'Accessories'
Right-click on Command Prompt and click "Run as administrator..."
- Please note if you are running Windows 8 you will need to press Windows Key + X and select Command Prompt (Admin)
In the command prompt, type the following command and press Enter:
bcdedit /debug off
Restart your computer.
Launch Steam and test the issue again.
Enable DEP
Data Execution Prevention (DEP) must be enabled to play on VAC secured servers. To restore DEP settings to default please follow the steps below:
Exit Steam.
Click the Start button, then 'All Programs', and 'Accessories'
Right-click on Command Prompt and click "Run as administrator..."
- Please note if you are running Windows 8 you will need to press Windows Key + X and select Command Prompt (Admin)
In the command prompt, type the following command and press Enter:
bcdedit /deletevalue nx
Restart your computer.
Launch Steam and test the issue again.
Restart your computer
If this is a problem for you on all servers then you can try fixing this problem by exiting Steam and restarting your computer.
Conflicting Software
This issue can be caused by third party software interfering with your game or Steam. Please restart your computer, then launch Steam and the game without running any other third party software.