Lagging in Export to Avi

Using ToonBoom Studio 6.0 and a bit less than halfway through a (approx) 2min 45s 2D toon, lagging starts to become apparent between the sound and picture (the picture lagging behind the sound, worsening as it goes (hence I assume the problem is throughout, but only becomes noticeable some way in). Tried the interminably long export (to avi) process twice and changed the soundtrack on second edit. Same problem same place noticeable lag. Searches came up with nothing which is why I posted it here.

Specs: Art imported from Photoshop cs3, Sound recorded on Audacity but imported to ToonboomStudio 6.0 as single track mp3 format. System - Win 7 64 bit, Intel i7 cpu, graphics card -Nvidia gtx 460.

Anyone have any idea what the problem might be?

Is it possible for you to do a test by importing it as .wav instead of mp3?
Please post your results.

Thanks for the suggestion. I will reply to this post again when I know whether or not doing that helped with the problem. (May take a while though).

I re-did the whole thing and used a WAV file format for the soundtrack, as per suggestion and exported it as an AVI again, on default settings. The picture lags behind the sound still.

Thank you for the update.

Please contact so that we can resolve this for you.