I have burned some games into CD-R with ImgBurn (and Padus plugin) and I've always used the same metod, same options.
First two games worked perfectly (Daytona 2001 and Sonic Adventure 2), and then, everything that i've burned into CDs won't work on the console, even when some games DO work on the emulator (NullDC), those games are: Ikaruga and Soul Calibur.
There are three games i've burned on CD-R and won't work either on the emulator or the console. (Bust A Move 4 (on the emulator, it gets stuck at "SEGA" logo, and the emulator's console starts showing errors, on the Dreamcast does nothing), Crazy Taxi (goes directly to the audio menu on both), and a compilation of Genesis games (insert game disc on both))
Bought Sonic Adventure (original GD-Rom, works like a charm) and the guy gave me a copy of Sega Sports Tennis 2K2 that won't work on his console, but I tried it and worked perfectly on mine.
With all of this, I don't know if the problem is while burning, the CDIs, the CDs i'm using (I've used Verbatim for all, and recently bought LG (only used on Ikaruga) or my console that just don't like the CDs.