An issue with your computer...

As the title says , im getting the error saying :An issue with your computer is blocking the VAC system. You cannot play on secure servers. So , i was playing for 2 months without this problem and i've been 2 times banned for ''leaving'' competitive games . I've already tried every solution (Steam , reddit forums etc.) but im still getting the same error . I really need some help to fix this

Restart your computer?