This will happen when you have switched on the firewall. You can go to settings and check which feature of Skype has been blocked by malwarebytes. You can resolve all problems related to malwarebytes when you find that any particular feature of any of the applications you are using in your computer is blocked. If you cannot bind on your own how to unblock the feature from malwarebytes you can contact the Malwarebytes customer Care team. The technical aspects of malwarebytes can be best it can cure of the customer support team members who have complete knowledge about the working of the antivirus