I'm responsible for Real Site protection in the Avast product. I have tested both products several minutes ago, and problem is only in MalwareBytes Web Protection activation process. It hangs the MB product completely.
If I disable Real Site, enable MB WebProterction and then enable Real Site again, everything works well.
Some more technical pieces of information:
Malware Bytes is trying to filter the UDP traffic (probbably DNS). It's same as Real site does. If two products try to capture UDP traffic by Windows WFP technology, a UDP packet loop can occurs if it's not implemented correctly. We found this problem with several other products. It's caused by two WFP drivers, when each capture UDP packet generated by other, drop it and generate new one. But this new one is presented to first driver, captured, dropped, generated again and it can continue indefinitely.
We discussed the problem with Microsoft WFP developers, to try to find solution for the problem. Avast had some protection against this before, but it doesn't work every time. Then we implemented new solution recommended by Microsoft. I can see from driver debugging, that it works, when both components are active (as described above). Problem is just in WebProtection activation process (not under my control, no time for reverse engineering).
Seems that the MB UDP filtering solution is not compatible with MS recommended solution, but anyway, if you use capture, drop, create and inject new packet scenario for the UDP traffic, it's completely wrong and can cause conflicts with many products.
I'll appreciate if an responsible WFP developer contact us. I'll be happy to explain to him how to to solve the problem.