Garageband/Logic Express export chopiness

[Coolguy204]

I use Garageband to record some of my music. It is enough for what i get done. I have a plugin called Omnisphere ($500) It is a fantastic program that professionals use. It seems that everything records fine in Garageband as well as playback from Garageband. But when I export as any file type (.MP3, .AIFF) it gets choppy in some parts. I bought the new 13" macbook pro. (4 GB RAM, 320 7200 RPM HDD, 2.26 C2D processor.) I don't see any reason why exporting should be such an issue. It works fine in windows when using FL Studio as the sequencer. Also Logic Express has the same issue. I do not see how this is an Omnipshere issue, but an issue with exporting projects to listenable file formats with both garageband and Logic Express. If anyone could offer any advice on what I should do or what company to contact (Apple or Spectrasonics) I would really appreciate it.