The Windows 10 Preview Build ships with a new feature but its pre-beta softwares always turn system to be unpolished and buggy so it is not good for production. If you have install it without in a virtual machine and keep experiencing occasional crashes and data loss, the bset way is to remove it and roll back to the original version. Here is the tutorial for that.
How to remove or uninstall Windows 10 and restore to Win 8.1
* The existing recovery partition of the Surface tablet has been overwrited by Windows 10, so you need to sign in with your own Microsoft account to download a recovery image file from Microsoft Support site. and create a USB recovery drive before the process.
Note: My Kingston Traveler is not working with message “Window failed to start. The boot configuration data for your pc is missing or containing errors.” and I have to use another.
* Remove Windows 10 Technical Preview
Make sure you have set up to boot from USB Flash Drive. The step will wipe your machine completely.
1. Plug the above USB HDD, power it up and press both power + volume down.
2. Tap Advanced recovery options > Command Prompt.
3. Input the following command one by one and press Enter to execute it:
select disk (n)
Warning: The (n) is the internal disk number, and you could run the list disk command to see its disk number.
To confirm the correct, run list partition and there should be multiple (5ish) entries.
The partition table will be wiped without return. Then turn the device off.
* Restore the opeating system
1. Press and hold the volume-down button while you press and release the power button. Then release the volume button when you see the Surface logo.
2. Follow the on-screen instructions to choose your appropriate keyboard layout and language from the list.
3. Tap Troubleshoot > Reset your PC > Skip this drive (if this option is at the bottom).
4. Select the currently installed operating system.
5. Tap Yes, re-partition the drives > Next > Fully clean the drive > Reset.
It will take a long time to complete the reset process and roll back to its original state (Windows 8.1 or 8).