Installing Windows 8 Developer Preview using Virtual Box on Acer Aspire 4820T

I tried to install Windows 8 Developer Preview using Virtual Box on my Acer Aspire 4820T laptop but kept getting an error similar to the one below but with a different error code:

Your computer needs to restart.
Please hold down the power button.
Error Code: 0x0000007F Parameters: 0×00000008
0×81613000
0×00000000
0×000000″

On googling the issue the only solution I found being mentioned was to turn on hardware virtualisation in the BIOS. However, it appeared that hardware virtualisation was automatically enabled, see here, and there were no visible virtualisation settings in the BIOS. 

So I went to the Acer support website, downloaded the latest BIOS and updated it from version 1.13 to 1.25. The computer restarted, I logged in, started Virtual Box and the Win8 VM and hay presto no error!