Disk Utility won't burn a .cdr image to DVD – why and what do I do?

I've burned DVDs before and I've had success with my MB Pro. I know the steps and use this support article as a refresher each time to assure I'm following all the steps. Yesterday and today I've tried to burn 2 different .cdr images made with Disk Utility to blank DVDs without success. It starts to copy and within less than 2 minutes, I get the message:

"Unable to burn 'xxx.cdr' (The disc can't be burned; it might be incompatible with this disc drive. Please try a different brand of disc, or try burning at a slower speed.)"

I tried 3 different blank DVDs (they are DVD+Rs 16x|4.7GB), 2 different brands (TDK & Sony) but no success.

What's going on and what do I do to troubleshoot and resolve this problem?

Thanks!