audio drags on XDCAM HD422

Hi:

I'm using FCP 7 to edit video we shot on XDCAM EX 1080p30 35mbs (variable). Our client sent us some footage shot on XDCAM HD422 1080p30 50mbs, and, for the life of me, I can't get the audio to stay in sync. I dropped it into a sequence with the same properties, but the audio drags. I tried using Compressor to convert it to the same XDCAM EX we were using, but to no avail. What am I doing wrong? It plays fine when I look at it right off the hard drive.