Are you consolidating clips at 15:1s will or if it’s only the sequence that will not consolidate?
What HD resolution are you working at, 145, 220?
Try removing effects or titles that could be causing the error–just for troubleshooting purposes.
What is the profile of the sequence> Are there titles, graphics, lots of imported stuff, any type of video or audio plugins?
Try to consolidating the audio only and/or the video…to help narrow it down…
Can you consolidate to local drives?
Michael