Hello
I spent my entire summer dealing with this problem. I bought my computer the first week of June and finally this past Friday (sept 23), I got the computer I had hoped to have back then. Do not waste your time resetting your computer. Do not waste your time fooling around with itunes settings. Do not waste your time with AppleCare. They will tell you it's your CDs, and IT IS NOT THE PROBLEM. The problem is the superdrive. You have a MATSHITADVD-UJ-845. This is your problem. Get a Pioneer DVD-RW-DVR-KO5. This will solve your problem. I had ticking sounds on about 40 CDS. I called AppleCare and they kept blaming my CDs. Finally another person on this discussion board, Stasia W, who had our problem had her MATSHITADVD replaced with the Pioneer and it worked for her. Now, when I mentioned this to Apple they told me they couldn't do the same for me because of the possibility that someone from Pioneer posted that. A local Apple repair service was kind enough to replace my UJ-845 with the Pioneer for a weekend to see if it worked and sure enough it did. They ordered the part for me and after labor it cost me $320.00. I will be calling Apple to see if they will pay for this since I was under warrenty but my hopes aren't up to high since they didn't authorize the change. As a matter of fact I asked my Apple repair service if this part will still be under warrenty since Apple didn't authorize it and they said "no". I finally have the computer I wanted back in June and it's the end of September. You will hear many suggestions about your problem but I believe this is your only solution. Look up Stasia W's clicking/popping discussion thread for more proof.