You probably should enable the "Capture alpha-blending windows" in the connection properties. Right-click on the connection in your address book, click Properties -> Additional properties and tick the "Capture alpha-blending windows" check box.
Alpha-blending windows are semi-transparent windows and menus.
You can share your address book in multiple ways. Please, refer to this tutorial. Personally, I think using RU Server for syncing (method 3) would be overkill, so you can just utilize your Dropbox or Box.net account to share the address book (method 2). Or, if you don't change the contents of the address book often, you can simply manually export/import the address book file (method 1).
Just to clarify, you cannot UN-lock the PC by sending Ctrl+Alt+Del command, correct? What happens when you simply click on a user icon on the Windows lock screen? When you are in Full Control mode, that is.