Heratech

 Fix found here: http://ubuntuforums.org/showthread.php?t=1381318

Basically I wasn't in the vboxusers group:

1) Check if your username is in the group: 

cat /etc/group | grep v*box

2) If it isn't add it and logout/login.

sudo usermod -G vboxusers -a YOURUSERNAME

VirtualBox 3.1.0 has been released!
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I followed the Linux instructions and installed it fine on Karmic 9.10 x64.

Do a "Microsoft Update" on Win 7. Install "Windows DirectSound" "ICH AC97" controller.

Or what worked for me (on windows 7 64bit) http://www.realtek.com/downloads/downloadsView.aspx?Langid=1&PNid=23&PFi...

Download the Vista/Win7 (32/64 bits) Driver only (ZIP file) file (AC97).

Trying to install Windows 7 in Virtualbox on Ubuntu. Kept getting this error message:

"A required CD/DVD drive device driver is missing. If you have a driver floppy disk, CD, DVD, or USB flash drive, please insert it now."

Solution:

I had to turn on passthrough on my dvd drive in the virtual machine settings.

See:

https://help.ubuntu.com/community/VirtualBox/Installation
http://forums.virtualbox.org/viewtopic.php?f=6&t=23157&start=0