I have been using Genymotion for about 4months now and all was well until I updated Virtual box to 4.3 . I did not like it because I didnt know how to run 64 bit OSs on it,so i
The following steps from an answer on the superuser community (https://superuser.com/a/1002243) worked for me. I'm running VirtualBox 5.0.10 on Windows 10, with the Fall 2015 Windows 10 update. In my case, the problem seems to be directly associated with the Windows 10 update. (I'm using VirtualBox in conjunction with Genymotion 2.6.0, but I don't think the Genymotion version is a factor.)
If the checkbox in step 4 was disabled, VirtualBox should work just fine now (no reboot needed). Otherwise repeat steps 3-4 for every network adapter you have (Ethernet, WiFi...) and always uncheck the NDIS6 checkbox -> apply -> check it again -> apply.