Circumventing system : The GAds account is getting linked to some other GAds account : Examples : Same domain used again & again, duplicate or very similar website contents, same or very similar ad copies, exact same payment method (card, etc) used too many times.
Malicious software : This pertains to using a tracking template (most tracking template providers are now flagged by GAds), or something GAds is detecting in the website : example : certain website templates have some hidden code, so try changing the website templates that you are using.
NOTE : Above are just a few of the most common reasons, there could be lots other reasons too, and the best way to solve it is by you experimenting with some of the common reasons (as above) and narrowing down to what could be the reason(s) your accounts get circumventing system / malicious software suspensions.
The problem is that when people get suspensions, most of them will keep repeating exactly what they've been doing and will keep getting suspensions. Do different things and do things differently, anytime you keep getting suspensions.