I have 2 desktops.
I downloaded win 10 preview on no 1
After a few minutes of log on time it just quits. The Drive light flickers but the scree goes to SAMNSUNG the Logo for the monitor MFG.
I figured it was something wrong on my hardware. I took the computer apart & did not find a hardware problem.

Computer 2 was running Win 8.1 without any problems!
I downloaded & installed Win 10 & the same thing happens!
So I went back to Win 8.1 & every thing is OK.

I waited a few weeks to see if MS had fixed the problem & reloaded Win 10 & the same thing happens!

This problem was reported many times but there seems no interest by MS or anyone else to fix it!

There are things in Win 10 that I like, but I can't tolerate the computer quitting when I am in the middle of something & I loose it all!
Then I have to hold the start button until the HD button turns off, then reboot.

After the initial failure it never occurs again on that computer session!

When I boot up agian later ,same thing happens!

There must be answer. The problem occurs on 2 different computers only when running win 10.