If this is a problem with your MacBook when Kaspersky's antivirus is installed but not when Avast is installed, why post it here? I would think Kaspersky's forums would be a more suitable place for it.
That said, I had been using a commercial version of Kaspersky's on my MacBook Pro for past 2 years with no such problem. It was installed on it by company I last worked for. Since license for that is expiring next week, I uninstalled Kasperskys a couple days ago.
Now, I'm trying to use Avast Mac Security in it's place because after 1.6 years of no job, I don't want the license expense for Kaspersky's. In doing that, I encountered a certificate problem with Firefox and Thunderbird while Avast is on it; but no problems with Safari.
So, I'm now debating on whether I want to use Safari while all my everything (bookmarks, login usernames/passwords,...) are on Firefox or bite the bullet and spend $$ I don't have for a license to continue using Kaspersky.