Joe_Intel:
I made it up to the trigger, i guess.
I have to correct my own post, it does NOT ONLY happen under Windows 8.1, also 8 is affected.
Besides that, everything works nice when you ONLY USE 1 FEATURE. Use the Bluetooth-chip with a mouse or sth, works perfectly as long as you WON'T use WIFI. Use WIFI and everything works perfectly UNLESS you use Bluetooth additionally.