I had Tech Preview build 9926 installed on a SSD which was extra so I can pop it in to use preview or pop Windows 7 SSD in. Well Sunday I was working and it locked up and when I restarted up it was like it couldn't find the OS. I did a repair yesterday and it's back up running. I had to install all the desktop apps again and the Metro apps were listed as owned and I had to install.
One thing that resulted is my screen display was real dim before and now the brightness I like was restored. It did 2 sets of updates before complete as I did install with the build 9926 ISO. I re-installed most of my apps and its working fine.