We give you a registry hack to get it working
Fix Windows 7 Switch User Disabled or Grayed Out
A client of mine recently had a strange problem in Windows 7 where he could not switch between users using the normal procedure. By default, if you click on Start and then click on the little arrow next to shutdown, you can choose Switch Users as shown below:
If this option is disabled or grayed out on your Windows 7 system, there are a few things you can do to fix it. If you're on a domain and want to use fast user switching, you can, but you'll need to edit group policy. Depending on your company, you may or may not be able to do that.
Also note that you can no longer edit this fast user switching option via the GUI in Windows 7. There was an option in Windows XP, but for some reason not in Windows 7. So you have to edit the registry or group policy to get it to work. I've also mentioned a small utility you can use if you don't want to edit the registry.
