Recently I was trying to create a 1:N field mapping from Account to Contact and could not because the Target entity fields were missing from the mapping window. (See the attached image) After a support call with Microsoft I was informed that Internet Explorer 11 is not a supported web browser version with Dynamics CRM 2011. The solution I would recommend for this is to use Google Chrome or a previous version of Internet Explorer like 9 or 10, which you can get to by uninstalling IE 11.

To uninstall Internet Explorer 11 (this will get you to IE 10) follow the steps listed below:
-Click your Start menu >> Control Panel >> Programs >> Programs and Features
-Click View Installed Updates at the top left of the window
-Search for Internet Explorer 11 >> when this appears select the program and click Uninstall

It is also a good idea to make sure your computer does not re-install IE11 on its own, as this is a recommended default setting. To change this setting go to the Start menu >> Control Panel >> Windows Update >> Change Settings >> Important Updates. This is where you can choose how you want your updates to be applied. I have chosen “Download updates but let me choose whether to install them”.