If you’ve encountered the error message:

You cannot play on secure servers for one of the following reasons:
•An issue with your computer is blocking the VAC system.
•You are unable to maintain a stable connection to the VAC system.
•You are running software that is modifying the game or is incompatible
with VAC.
For more information visit:
https://support.steampowered.com/kb_a rticle.php?ref=2117-ILZV-2837

it means Valve’s Anti-Cheat (VAC) system has detected modifications or interference in your game files. This is common in Steam games like CSand often indicates the presence of third-party software altering the game environment. Here’s a breakdown of what the error means, common causes, and the steps you can take to resolve it.

If you’re experiencing issues such as missing textures, absent game content, or crashes, follow these steps to have Steam verify your game files are correctly installed. This process can help resolve many common issues and improve game stability.