At time of writing, I tested this with the latest version of Virtualbox v4.3.22 and Windows 10 Technical Preview Build 9926.
Correct steps to failure
- Set up the 32-bit virtual machine
- Select the 32-bit technical preview ISO.
- Start it up and watch it burn.
Your PC needs a restart.
Please hold down the power button.
Error Code: 0x0000000A
The fix for it
This baffled me for some time because I thought VirtualBox was buggy or something. Oddly enough, telling Virtualbox to expect a 64-bit operating system will fix it.
I'm not sure if this is a bug within Windows 10 (because it worked fine in previous technical preview releases) or a bug with VirtualBox. Either way, hope it gets fixed before Windows 10 gets released!