Anybody else keep getting this? My HDMI is fully connected and I can't figure out why it works when I start up my computer but gives this error after my computer wakes up from sleep mode.
I always had my DK2 connected to the second display port of my 970 card (which has 4 display ports - DVI - HDMI - HDMI mini ...). It could have really happened after the last update, that it started displaying this error message. I got rid of this problem - for some unknown reason - by connecting the DK2 to the third display port (i have different HDMI adapters attached to the different display port connector types, to have normal HDMI plugs available). After that, my DK2 kept working again normal and the HDMI error message is gone since.
Went to bed, woke up this morning, booted up the PC with the rift and all is well again. (even tho I rebooted 5 times last night, and even pulled the power on the PC)
I'm having the same problem - filed a support ticket last week and still no response. Reinstalling oculus + restarting a few times seems to fix it, sometimes.