I have noticed that when I switch styles that have a C/D section I can constantly reproduce the the "Access violation" error as well.

Example: I wanted to create a "heavy rock" song, the tune sounded ok. Out of curiousity I decided to hear it as a classical tune. I changed the style to a classical style (did not matter which one) and constantly got the "Access violation" error when I clicked play until I changed the C/D section to A/B section.

I did notice the following: error flash "unable to pick a drum audio bar from bar 97"

I also noticed that Realband will convert the C/D to an A/B section and has no problems switching styles.