I just found out the hard way, I spent like the whole morning fixing the viruses malware on my computers. Even though I had Symantec antivirus but that alone still couldn’t block the malware, so I needed to install malwarebyte back, and it did the job side by side with symantec. There were a bunch of viruses and malware trojans adwares whatever you call it, attacked, invaded my computer I had to unplug the internet from the infected computer, took the harddrive out and put it on my i7 system to decontamination first scan it with malwarebytes then symantec antivirus, then again the send time same thing ensure none left, then put the hard back to the old computers:) done 🙂 Keep in mind some viruses will freeze froze your computer during decontamination process, so might want to run malwarebyte while symantec is disabled.