DRM protection

I’m a new user of Cubase 5 Essential, and am having problems exporting a mixdown that I can burn to an audio CD in a format that will play on conventional CD players and Computers. Every time I attempt to burn a disc I get the message “The audio file is DRM protected and cannot be burned to disc.” This occurs with .wav and .aif files but not with .wma files (which won’t play on a CD player). Can anyone tell me what this means, and how to overcome the problem?

I can simply share that DRM files were made available to me the last time my CD was mastered. They were used for auditioning, before accepting the finished masters and of course, before payment! Yea, they are protected files…so someone has protected them for a reason.