from the beginning of the win 10 tp program:
thinkpad T61 with hgst 7k1000. build 9841 worked. build 9860 worked with a couple of problems which were reported/resolved.
installed build 9879.
all updates to builds have been installed.
at the first wake from sleep event, BIOS could not find the HDD, specifically error 2100. tried to get drive back to life in several computers, using several differnt techniques; its bricked, does not spin up does not respond to commands, nothing can see it.
found another drive same hgst 7k1000 model. repeated above. HDD number 2 is now bricked too.
switched to a thinkpad T400 and yet another hgst 7k1000. repeated install as above. HDD number 3 is now bricked too.
have NEVER before in many many years experienced a travelstar failure.
this is a $erious issue that needs attention ASAP. microsoft please respond!!