For some odd reason a rash of Seagate HDD failures. The owners all thought it was the update but cloning the drive (most used that 50 buck WD laptop drive, 500GB) fixed it. To make matters more odd, the Seagate passed the maker's diagnostics but failed other tests by other authors.

So this is not to write this is your issue but check out the PC's HDD maker. If it's a Seagate, may want to clone it while you can.