Problem with sound quality of last couple of tracks when burning CDs

I have burnt about 50 CDs over a period of a week using i-Tunes and good quality CDs, and have noticed that there is a problem with the last two tracks on most of the CDs. They a not a clean sound, like there is static in the track. I'm using 80min CDs and they are the same brand I have been using for ages and have never had any problems. Any suggestions? I don't understand why the quality of the last two or three tracks is completely different to the pristine quality of the previous tracks. I have a Macbook Pro, with all the latest updates including i-Tunes.

Those songs that had static in them, how is the quality of the discs? Sometimes if they are scratched, that can cause skipping or staic when they are played/ripped. Have you tried playing around with the mport settings in iTunes at all? There's an advanced setting in there called skip-reduction or something like that, I'm not in front of it at the moment. Try re-ripping with that and see if there's any difference. Sometimes it works, but sometimes it doesn't. And yes, it could happen where a majority of the CD tracks sound nice, but some don't; some of my older CDs are like that too.