If you join in the server and you find this issue with your computer is blocking VAC servers,read steps:
1. "Windows key + R" or "Search Run"
Type:
C:\Program Files (x86)\Steam\bin\SteamService.exe /repair

2. Windows key + X then CMD Prompt ADMIN or Search "CMD and And Run As Administrator"
Type (after typing one line click enter and repeat):
bcdedit /deletevalue nointegritychecks

bcdedit /deletevalue loadoptions

bcdedit /debug off

bcdedit /deletevalue nx

bcdedit.exe /set {current} nx AlwaysOn

*Instead of "bcdedit.exe /set {current} nx AlwaysOn" you can enable DEP*

***HOW TO ENABLE DEP PC Settings < Advanced System Settings < Advanced < Settings < Data Execution Prevention < Click Second Option < Apply < Ok

3. Open Steam < Library < Right click Game < Properties < Set Launch Options < Deleted "-insecure" < Click "OK"

4. Open Steam < Library < Right click Game < Properties < Local Files < Click "Verify Integritiy Of Game Cache"

And after completing all steps RESTART your computer and hope you won't get this problem! ;)