I had the same problem in Win8 with multiple Firewall NDIS Filter Miniport on Win8 Device Manager. I did similar. I went Avast settings and disable the self defense mode, it popped up a window asking if I was sure I wanted to do this, I clicked yes. Then went to computer properties to Device Manager, down to the network adapters, clicked on one of those warnings for the miniport, and doubleclicked it, where there was a reinstall button, clicked that, it reinstalled, then the Device Manager refreshed itself and all the miniport warnings went away, did a restart and it worked fine. Went back into AVAST settings and re-enabled Self Defense mode. Beats me. I encountered this problem when I was installing some HP driver/software for my wireless photosmart printer. Beats me, for what's it worth...