I tried my first attempt at running an application in user mode yesterday and learned a couple of things. You can find both of these things in the documentation, but who actually reads the docs? If you want to test out an application in user mode, but don’t feel like going through creating and copying the xml file to the proper folder, there is a way around this. I copied the exe file into the “T” users Documents folder (anywhere else would work to). Then I clicked on the “Enter User Mode” shortcut which you have on an administrator account. Once you have been switched over to user mode then hit “Ctrl-Shift-Esc.” At this point you will see the task manager, which will allow you to browse to and start the exe you saved earlier. Simply hit Ctrl-Alt-Del to get back to Admin mode. If you try to switch to user mode and you get an error message that says something like “object is in an incorrect state” (or something like that, I can’t remember it exactly). You probably changed your table user account password. To fix this problem you need to use SurfUser.exe. Change the directory in your command line to the folder containing the surfuser.exe executable and run the surfuser regen command. The surfuser app will regenerate and register that new password with the system for the default table user account. You can change the default password for the table user account, but you must use the surfuser app to do this. The docs will tell you how to go about this.
P.S. Don’t forget to make sure the bios on your surface unit is updated to the latest version which at the time of this writing is 0206. See “BIOS updates for a microsoft surface unit” in the SDK docs for further details.