Sound distorts when playing CD's
 

In my '01 996 TT with NAV (in case that matters):

Whenever I play a CD from the 6-disc changer up front, the sound begins to distort after 2-3 songs.
It does this on most CD's.
Also, disc 5 of the changer will only load 1 out of every 3 times, regardless of what CD is actually in tray 5.

Any ideas / suggestions? Do I need to replace the changer? How hard / easy is it?
Thank you for your input.

I had a similar problem... the sound was slowed down and low pitched. I took it to the dealer and they said there was some electrical problem and had to replace the entire cd changer. it was under warranty though so I dont know how much it would have cost... sorry I couldnt be of any more help.