Once before I had that error when I had a problem with sound and I set a sequence up as mono because we only had left channel in the mic recordings. It was eventually fixed, but while it was still messed up it gave me such a pain, check to see if you're sequence is in mono, and if it is, change it back to stereo. i don't know why this works, but it did for me. and if it's not that, you'd have to wait for a reply from someone who knows the program better, sorry.