Backsound randomly doesn't work (case 3040)

Hello,
Occasionally, when I run a questionnaire or experiment file, the file will run but will not play the backsound. No error message comes up saying the backsound couldn't be found - it simply doesn't play. Each time, when I close MediaLab and reopen it, and try the same questionnaire or experiment file again, it works. The sound will play only after completely closing the program first. This has happened on at least two different computers.

Any ideas on how to prevent this from happening at all?

Thanks!

This is the Customer Support Manager at Empirisoft. Can I be of service regarding your question about using backsound?