Problem with coreavc 2.5 and ac3 filter

[cvrak]

I'm using bsplayer and coreavc decoder for more than 2 years and suddenly I faced noise distortion in 1080p mkv files. This distortion occured sometimes, and I couldn't find a solution. Some days ago i changed some setting in ac3 interface , but the problem remained.

Yesterday when I tried to play a 720p 5.1 mkv file, I couldn't hear the sound. I had to go to audio/audio streams and there were AAC 2.0 & DD5.1 options. I choosed DD5.1 and the sound was ok. But in the Options/filters/AC3 filter the input was 2 channel, eventhough the mkv has 5.1 audio.
I uninstalled and re-installed bs player but the problem remained.
I uninstalled bs player, coreavc pro, ac3 filter and re-installed everything more than 5 times. The problem remains and now in Options/filters there is no AC3 filter, eventhough the ac3 filter is installed.

What did i do wrong?
What installation procedure do I have to follow in order to use bs player, coreAVC and AC3 filter?

Pls advise