Hello
First when you are posting an error message the systemm config would be great. It just makes things easier and defenetly you get more answers. I mean which software ( Xpress/MC)and version and also is there any I/O’s connected to the CPU which kind drives you are using?
But buffer overrun error can be caused by overloading the system’s playback capabilities. Normally this kind of error happens when you have too many streams in your timeline but according the picture in your case that’s not the issue. You may have bad RAM in the CPU. You can try replace/reseat the RAM and the error should go away.