Perhaps he's trying to install a VM inside of Tech Preview. In that case, it definitely would cause issues as it's not an official release OS. VM programs often install services for things like network stuff and disk drive access and such.
vbox 4.3.16 is having issues with security software. i had to go back to 4.3.12 to get anything to work. check the vbox forums, they're working on some new updates 4.3.17 didn't work for me either.
I ran Windows 10 on virtualbox and vmware workstation 10 with no issues. both are up-to-date. no issues at all. for virtualbox, select as if windows 8.1 x64 since I got windows 10 x64. for as vmware workstation, select windows 8 x64.