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.

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Some days it aint worth gnawing through the straps

Just uninstall those hax you borrowed off Marten, job done.

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Yeah, a few of the more dodgier players have been getting this. I noticed Paranoid did last night while he was upgrading my sentry.

Yes Im gonna slap, kick and ban you Sponge.

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"Sincerely, and go fuck yourself;

I've gotten that error couple of times... Disappears after restarting the PC

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Don't make decisions when you're angry and don't make promises when you're happy.

disabled aimbot on my stickie launcher.. bingo !
actually not tried yet.. maybe tonight

..and eM, did u quit playing TF2 cos Marten dumped you for Zoey?

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Some days it aint worth gnawing through the straps

I wish, just better games to play atm

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Don't make decisions when you're angry and don't make promises when you're happy.

What do you mean?

Oh, you are talking about all them kritz that you eat on FM

Anyways, it's kinda hard to give someone kritz who hasn't been playing for like 4 months

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Bootyglasses:

Is it popcorn time again?

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"Sincerely, and go fuck yourself;

There are other games?

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Some days it aint worth gnawing through the straps