In the past, I've used Roxio (now Sonic) Easy CD Creator to burn CDs/DVDs for audio and data. But yesterday, I needed to burn an ISO image of the new Windows 7 beta to a DVD. Every time I tried with Easy CD Creator, it would tell me to insert a blank DVD even though it was blank! I tried 3 different brands of DVDs which were all new and never used. Apparently, some CD/DVD burning applications are not too user friendly depending on what you are trying to do.
So, I found a trial version of an independent ISO burner called ImTOO ISO Burner. I was able to burn the ISO on the 1st try with no issue. It recognized the same DVD that I was trying with the Roxio application.
I'm sure there are other independent ISO burners out there but ImTOO ISO burner did the trick. You can download it here: ImTOO ISO burner