Well, I've been around the block a few times on this one. I wanted my PCs to be fully protected, so I upgraded them from the free version of Malwarebytes to the premium version 3. Soon thereafter, my PCs began slowing down, not responding, and showing a Malwarebytes error message saying that Web protection had been turned off. I tried to turn it on, but it would either not respond or just say, "starting," and wander off into bitspace.
I contacted Malwarebytes technical support and they gave different suggestions on three occasions. I reinstalled, tried changing settings, rebooted, and so forth, to no avail.
To the chase: Finally, after a lot of research on the Web, I discovered that this issue has been known since at least 2014. It's this: Malwarebytes and Kaspersky antivirus/ Internet protection simply do not like each other. The solution was to uninstall Malwarebytes.
Question #1. Since this is a years' old issue, why doesn't Malwarebytes technical support know about it?
Question #2. Since this is a years' old issue, why haven't Malwarebytes and Kaspersky gotten together and fixed their incompatibility?
Bottom line: If you use Kaspersky antivirus, don't upgrade your Malwarebytes to the premium edition. If you already did and are getting these error messages and pulling out your hair, uninstall Malwarebytes 3 and ask for a refund.