Virtualbox is a wonderful tool for pc virtualization. I use it all the time for testing installers and just general I don’t want to hose my PC if this goes pear shape type stuff.
It’s great for devloping Windows software that needs to work on different versions of the OS too. I test XP, Vista, 7; x32 and x64 versions without breaking a sweat.
However once up upgraded to the new version 4.0 of the product the some networks were no longer operational. Specifically those using the dhcp on host only connections.
I thought this may be an issue with old guest additions which I then proceeded to upgrade. Unfortunately this did no turn out to be the issue so I proceeded to give up an just use other network types.
However today I stumbled upon the solution and it came from somewhere completely unrelated to virtualbox.
The posting of the solution can be found on a forum My Digital Live here.
There appears to be some bug within the source code which the user has devised a patch for.
The Solution
Windows versions of Virtualbox only
- Download the compressed patch from http://www.4shared.com/file/EFsSxJaV/vb4dhcp_patch.html
- Extract the program using 7-zip
- Open command prompt as Administrator and navigate to the directory where you extracted the program
- Run the extracted program vb4dhcp.exe passing a single argument to the VBoxC.dll
vb4dhcp.exe "C:\Program Files\Oracle\VirtualBox\VBoxC.dll"
No you can run Virtualbox and it’s dhcp server runs again. 
Update
Virtualbox 4.0.4 has been released and this regression has been fixed. Download it now.
