My Surface Book crashes repeatedly during sleep, and occasionally during use. I also occasionally get the hot bag issue, where I close the lid, put the SB in my bag, and two hours later I could fry an egg on the SB and the battery is depleted. I have run the DSIM procedure and I have reinstalled Windows completely. The latter reduced the crashes to about once per week, for maybe four weeks. Now my SB is back to crashing every day or at best every other day. Typically, I use the SB, close the lid, and when I open the lid again the next day the screen is black although the keys light up. Press the power button for 30 seconds, reboot, and it's fine again until the next spontaneous crash. No error messages except "Windows was not properly shut down" and "The previous system shutdown at ... was unexpected". Since my warranty is about to expire, I am now sending back my SB and getting a replacement. I have absolutely zero confidence that the replacement will be any better than the POS I have now. The Surface Book is easily the least reliable computer I have ever owned. It is less reliable than several computers I own that cost a fraction of what the Surface Book costs.