FCP 7 and TASCAMDR-40 Sync Issue

Hey all,

I know similar problems abound here, but I've tried many solutions and nothing's worked, so I'm giving it one last shot before I just live with this problem or start returning equipment.

We shot several interviews with a 5DMarkII at 23.98 fps with 48khz audio. Recorded audio using a Sony Lav into a Tascam DR-40 at 48khz as well. Encoded footage to Apple ProRes LT, and sequences match the footage setting first.

The sync drift starts after about three minutes. Really frustrating. I've used other Tascam models before and not had this problem. Does anyone have any ideas?

Thanks a ton.

Ben