Hi Prog,
I spent some time in the weekend to diagnose what the trouble could be and I come out with some good news (at least I home).
I noticed that when I have the screen blank and no signal/quality with the latest version 6.84, 
switching to  driver "Microsoft compliant BDA driver" restores functionality !!!   
Switching back to "Avermedia" turns the screen back and makes signal and quality disappear.
Switching again back to "Microsoft compliant BDA driver" again restores functionality.
So it seems there is a problem within the AverMedia driver in versions >6.83.
By the way, I seem to remember... didn't you post a note regarding Avermedia drivers in one of the latest releases?
Moreover, while using the Avermedia drivers I was not able to find a repeatable pattern of cases where version 6.84 would work or fail, i.e.:
- Installed 6.84 version on top of 6.81 -> ok
- Tried to standby the laptop and once back launch 6.84 -> ok
- Tried to hibernate the laptop and once back launch 6.84 -> fail
- Deinstalled 6.84, cleaned registry and reinstalled 6.84 -> fail
- Deinstalled 6.84, cleaned registry and reinstalled 6.81 -> ok
- Installed 6.84 version on top of 6.81 -> fail
As I wrote earlier, only switching to "Microsoft compliant BDA driver" let me use 6.84 with no troubles.
- Finally, I also tried to check codecs, but I use the same between 6.81 and 6.84, as follows:
     Video renderer	Enhanced Video Renderer
     Mpeg-2		Mpeg4 Decoder DMO
     H.264/AVC	DivX H.264 Decoder
     WMV		VMVideo Decoder DMO
     Mpeg4		Mpeg4 Decoder DMO
     Mpeg43		Mpeg43 Decoder DMO
     Mpeg4s		Mpeg4s Decoder DMO
     H.263
     VP6
Let me know if I can help you by performing some more tests.
     best regards