Last week on the our podcast we discuss many of the problem in the Windows 10 Technical Preview, ironically just as we completed the recording of the show Microsoft released build 10061 of Windows 10 which for me is substantially better than the previous release (but not so for co-host Jason, more on that on this week’s podcast).
Despite the improvements there are still issues with build 10061 especially around the lock screen. Microsoft have just fixed one of the lock screen issues in build 10061 via a Windows Update. KB3055415 fixes an issue where you get a black screen after unlocking you PC.
You should see the update download via Windows Phone update.
The lock screen in Windows 10 Technical Preview Build 10061 might appear as a black screen with a mouse cursor
When you sign out of Windows 10 Technical Preview Build 10061 and return to the lock screen, you might see only a black screen with a responsive mouse cursor. Pressing the Alt+Tab keys or the Ctrl+Alt+Del keys has no visible effect.