Hi there.

If you are experimenting with Tablet and desktop mode the mechanics are a bit convoluted.
First I'd apply Brink's tutorial which allows you to toggle to and from start menu or start screen mode without re-booting. He's fixed it for build 9926 too.

Now to get INTO tablet node from desktop - open the Notifications icon (why notifications Ms - that's CRAZY !!!!) and choose tablet mode.

Note to STAY in tablet mode set the system to use the start screen as per Brink's convenient toggle function. Otherwise you'll get metro apps windowed.

To switch BACK again you now have to go into PC settings - there's a switch - set tablet mode to OFF. Why the tablet mode couldn't have a simple on off switch from the SAME place is beyond me.

While this works at a TECHNICAL level Ms need to bring some "ergonomics" into their design -- this is one of the most convoluted means of achieving what should be an easy simple switch that I've ever encountered. Ms while testing get some REAL HUMANS involved not so much as to test the technical part of the build but just for easy USEABILITY. !!!