As the titel say's. I was using Windows 10 TP Enterprise build 9860 for a while now on the 2. HDD of my Laptop wile on the Main HDD Windows 8.1 Pro is installed. Instead of the DVD Drive, I changed that casing for to use with an 2. 320GB HDD running the TP. With the build 9841 I was use both OS'es with no problems till today with the build 9860. Tryed to recover the Windows 8.1 Pro but neither way worked: neither Recovery, nor System Restore, nor Repair, nor Refresh. Didn't try to use the USB Stick for recovery yet, will do that tomorrow. I could simply recover from an saved Clone, but that wouldn't give me the infos what could be done else using the available tools from MS, which is what most of the 'normal' users of MS would try to use from which I've a lot within my customers. And what happen to me could happen to many pthers as well. I didn't condem Windows 10 TP for that, it's just an Alpha or even a Milestone which hyas a lot of bugs and glitches! The warnings MS was given really were not just for nothing and users should really aware about those.