Remixing Acapellas In Logic 7 Options

[Derok]

Hello,

I am looking for any advise from folks who are using Logic for doing remixes with acapella audio files.
I've noticed that the timing of Logic's metronome doesn't stay consistent with the timing of the audio that I imported into the arrange window. I've gone as far finding the full music versions of certain tunes I want to remix, to help establish the bpm; but the sequencer always gets out of sync with the track after going for a while. Is there something inside Logic that I need to set up in the "preferences" to keep things synced within the program. Any syncing tips would be deeply appreciated.

Thanks,

D.