
Clicking the [Get help with this error button] brings this very helpful box:

Tried restart the laptop (which is shutdown every day anyway), stopping the update service and removing the update cache, tested the drive with chkdsk, sfc /scannow and nothing is wrong...
Other Windows devices in my LAN work just fine - Surface 2 (Windows 8.1), HP Microserver (Windows Server 2012 R2), HTPC (Windows 7 SP1)...
Any ideas?