Microsoft recently released Windows 10 Anniversary Update (build 1607). It causes disk freezes on Lenovo X230 laptops (and possible data corruption).
Solution: install the Intel Rapid Storage Technology drivers from Lenovo's support site. You'll need to to this manually, because Lenovo's System Update tool won't recommend them.
WARNING: running the driver installer isn't sufficient. It just dumps the drivers into c:\Drivers. You then need to manually apply them by updating the AHCI driver in Device Manager (the readme files for the drivers explains how to do this).
Link for the 64 bit Windows 10 compatible Intel Rapid Storage Technology Drivers: http://support.lenovo.com/us/en/products/Laptops-and-netbooks/ThinkPad-X-Series-laptops/ThinkPad-X230/downloads/DS103077
And the all important README file, whose steps must be followed if you want this to actually work: http://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles/gmio10ww.txt
Oh, and don't sell your AAPL stock yet, because Microsoft and the PC OEMs clearly still have quite a way to go to catch up.