I have the same issue and I am running Windows 7 with Virtual Box 5.0.20.
OS: Winodws 7 Enterprise SP1
AntiVirus: McAfee VirusScan Enterprise + AntiSpyware Enterprise 8.8
VPN: Cisco AnyConnect Secure Mobility Client 3.1.05170
Running CentOS 7 as a guest OS.
The only version which works for me is 4.3.12. Anything else running >= 4.3.14 do not work for me.

- 2016-05-26 16_18_53-VirtualBox - Error In supR3HardenedWinReSpawn.png (16.92 KiB) Viewed 3230 times

- 2016-05-26 16_19_04-VirtualBox - Error.png (25.88 KiB) Viewed 3230 times