My problem when playing TF2

I have been getting this problem for about more than two months where I get this message "An issue with your computer is blocking the VAC system you cannot play on secure servers".I have tried steam support to fix my problem by using the command prompt but it didn't work. This is not to be confused with hacking I am for some reason able to return to a server once I get disconnected but I continue to get this message.I'm not the only one who has this problem such as both Team Fortress 2 and Counter-Strike Global Offensive players have had this problem.Apparently it's a common bug where I need to restart Steam/Computer, but I keep getting this problem.I'm wondering if anyone here can help me fix this issue so I can play TF2 more often.

 

I know you've already gone through all the steps in this Steam Support thread to no avail. Have you looked through this list of programs that may conflict with Steam?