http://kwsupport.com/2011/08/sbs-2011-essentials-hangs-on-install/
When installing SBS 2011 Essentials (either on bare metal or in a Hyper-V environment), you may very early on in the process encounter a situation where the installation seems to hang. The screen displays “Please wait while the installation continues”.
If this is happening to you, check to see if your network card has been assigned a valid IP address. You can do this by pressing Shift-F10 to display a command prompt window, and then type ipconfig and press enter. If the network card has an IP address starting with 169.x.x.x then you do not have a valid IP address.
Remember that SBS 2011 Essentials, by default, expects to be connected to a router that is issuing DHCP addresses. This is unlike SBS 2003/2008/2011 products where the SBS server handled the DHCP role.
To fix this situation, either (1) ensure that the SBS 2011 Essentials server is connected to a router, and that the router has the DHCP role enabled, or (2) assign a static IP address to the NIC card on the SBS 2011 server.
To do option 2, from the same comand prompt window you just opened up, enter the following command:
netsh interface ip set address “interface name” static ipaddrsubnetmask gateway metric
Note: The interface name is obtained from the output of ipconfig (see above example).
For example, if you wish to assign a static IP address of 192.168.1.2, a subnet mask of 255.255.255.0, and a default gateway of 192.168.1.1, then enter the command as follows:
netsh interface ip set address “Local Area Connection” static 192.168.1.2 255.255.255.0 192.168.1.1
For more information, check out the SBS Official Blog post on this subject!