Q: 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.