Step 1 First thing first, do Valve's official fix and reboot your computer:
Step 2 Now, as a Windows 8 user, you probably have "Smart Menu 8" installed.
A software released by iOBIT.
IOBIT is known for making software who loves to mess with your PC, so make sure you uninstall any IOBIT software, INCLUDING StartMenu8.
Step 3 I had the VAC issue, and then did this.
VAC error is no longer a problem for me.
Do Valve's Official Fix
Uninstall any IOBIT software, such as StartMenu8
Verify game files
Enjoy your VAC Supported games #CSGO :)
Locate both Steam.
exe and csgo.
exe and make sure they always run as admin.
Uninstall CCleaner (This does "fixes" on the registry, and it makes no difference if you bypass Steam folders)
Hope this works for you too! =)
Thanks This guide was originally written by: area
Thanks so much my friend.