Windows watermark on homemade CD's?

I regularly purchase and download mp3's from a church Web site, and burn them onto CD's so I can listen to them in my car. This particular church allows 10 free copies for each file purchased, so I borrowed our church duplicator to make some copies of my CD's, and the duplicator would not make copies.

I've also purchased CD's from this church and have not had any problems making duplicates of those, so I'm pretty sure the problem is with my PC, not their mp3. A friend has mentioned that he thinks it's a watermark put on by Microsoft (Windows). I'm using either Roxio or CDBurner programs to create the disks on my WinXP Pro PC.

Does anyone have suggestions as to how I can get rid of whatever makes my homemade CD's not copyable?