On July 10, Microsoft officials said they had identified the issue causing some users' Surface Pro machines to randomly hibernate/sleep. Officials said at that time they were testing a fix for it which they'd deliver via Windows Update. On July 12, BryanH said on the Microsoft Answers forum that Microsoft had not yet included the fix in the latest bunch of updates delivered this week on Patch Tuesday.
Microsoft introduced the newest member of its Surface family, the Surface Pro -- which it is positioning as its "most versatile laptop" -- in late May. The device is the successor to the Intel-based Surface Pro 4.
Some unknown number of Surface Pro users began reporting in late June that they were having hibernation/sleep issues with the new devices.