When using mkv trimmer, if edit something out in middle, lose audio at end of video for about last 45 seconds. I take cartoons that I download off the internet that are in mkv format - single audio (a_aac) and I edit out the repeat in each episode (the title sequence), and the credits.
If you need me to send a copy of a file, I can, I have tried on multiple computers, and different OSs, and get the same result. Tried older copy from site, and newest, and same results. Sometimes it will work, but most of time will not. I have tried on XP and Vista.