****SOLVED**** - (for me anyway)
Although i was having difficulty with using Smartglass on my Nokia Lumia 920, it might help to mention here that i solved it by carrying out the following:
1. Uninstall Smartglass from phone - got to games, and under collections press and hold the Smartglass icon
2. Reboot phone by pressing power button and volume down until switches off, then off, then on and then releasing both buttons. It will reboot.
3. Re-install Smartglass
I'm nor sure if this was a hard reset or whatever but i found that the time and date were out by about a couple of months although it was on automatic and in the correct time zone?!? Apart from that the phone seemed untouched.
4. Turn on Xbox and download new dashboard firmware (it will appear automatically as of 27.11)
5. On Xbox go to settings, then account security, and turn on requirement to enter username and password every time you log on.
6. Sign out.
7. Sign in and enter username and password and tick remember password box.
8. On phone start Smartglass
This worked for me but i'm not sure what it was that fixed it. If you want to copy everything identically then re-install Smartglass and then uninstall again between point 1 & 2 but i don't think that's necessary.
To hard rest the iPad i think you press the power button and then home button together until it switches off and then release the power button while still holding onto the home button for 7 seconds and then release home button but check this out first.
Hope this helps.