Playback horrible still

Just downloaded the latest version of Muse-score last week having upgraded to a new computer which I checked the requirements of the program and the computer exceeds this by far.

Thinking these problems were related to my older computer with processing speed sill above requirements, UI find after using for about 30 mins meaning inputting notes, changing dynamics and playing back that which had been written, the usual interrupted playback started. The blue playback bar takes ages to run past a 4/4 bar at 120, after using the program for about 30 minutes and the only way to stop the distorted playback is to shut the program down and start again. This works for playback if you don't edit the score. If you do the problems described above happen and I have to shut down the program.

Playback seems to be a major stumbling block with the program and it's causing havoc trying to write large orchestral pieces. I have a new computer and it;s not even a week old. The processor and RAM exceed all requirements and to make doubly sure, all the stuff I don't use such as games has been removed by the technician to reduce any CPU usage.

Still dreadful playback.

Another issue that has occurred is the wrong sounds coming out of the instruments on the score even though they are assigned the right sound from the menus. Oboes started playing back as trumpets. Oh joy.

What is going on here with this? Can anyone advise on how to make this program playback properly for longer than 30 mins or to playback whilst editing and adding to the score?