Since I couldn't find anything about this on hexus:
Be wary of installing windows update KB3035583. It was "optional" at first, now it's marked as "important" by MS so it might automatically be installed.
Microsoft describes it as "enables additional capabilities for Windows Update notifications in Windows 8.1 and Windows 7 SP1" (link).
What it actually is? A Windows 10 downloader that phones home all the time and displays nag screens.
Heise did a report on this already (in german ; link ; google translator version ; bing translator version)
Seems like MS wants to shove Win10 down our throats by all means possible..