Final Cut Export problem

[FilmerD]

Finished up an edit tonight. Went to export (through Quicktime Conversion), only to view the end product (exported Uncompressed 8-bit, 480x320, AAC audio) and see that a clip I had placed starting at 00:00:13;27 had been moved about 1 second over, making it out of sync with the song I used (Only the clip had been slid over, nothing else in the edit had changed). I have had this problem before, at pretty much the same spot and it frustrates me to no end considering I can no longer achieve the end product I'm trying to export with the program. I have no idea what the problem could be stemming from, considering everything else in Final Cut works fine otherwise. Please advise.

My specs are MBP, 2.33 GHz Intel, 2 GB Ram, OSX Version 10.4, using Final Cut Pro 6.0 under the Final Cut Studio 2 suite.