At this time opal12.opalstack.com (Washington DC shared hosting) is being blocked by Malwarebytes. The cause was an outbound SSH attack from a compromised customer shell account which caused the server to be listed in a major block list. As a result visitors who use Malwarebytes may see a warning when visiting sites hosted on opal12.
We're working with the block list operator to have the server delisted and expect to have this resolved within the next couple of days.
In the meantime, you may be able to work around the problem by adding your site domain and/or server IP 207.244.121.250 to your Malwarebytes exception list.