My disappointment in Ubuntu BURNT CD/DVD BLANK

Hi everybody
I had a worse disappointment in my ubuntu life t he other week. Though a lecturer by profession in a homoeoapathic medical college, I always used to cater the the linux needs of everyone.
One nun from dept of Psychiatry was having ubuntu on her lenovo machine. It developed a technical snag of wireless dis connectivity and I was called upon to rectify it.
I thought of solving the issue by reinstalling the OS. Before re installation I decided to make the backup copy of the documents folders which amounted to around 16 GB.
I purchased one moser baer DVD and inserted it into the dvd drive of the lenovo machine,immediately the default cd dvd creater of nautilus popped up and asked for the command to proceed.
I selected the folders to be burnt and hit the burn radio button and went out for a late party.

When I came back around at midnight, I found out that there was an error message citing that all files were not burnt successfully. I ejected the DVD and once again i loaded into the dvd drive, immediately the default pro gramme of CD DVD creator popped up. I double clicked the DVD icon which was displayed in th window and lo! i was overjoyed to see all the folders and files in the DVD.
I completely ignored the warning message. In order to be sure I once again reloaded the DVD and found out that there all folders are there in the DVD.

The next day early morning I reinstalled the ubuntu successfully. When i inserted my backup dvd, I was shocked to find out that my DVD was blank.

I did some investigation to find out the reason for this phenomenon. I found out that when a CD or DVD is selected for burning, the folders and files to be burnt are stored temporarily in the RAM of the computer. each time when you eject the CD/DVD, the folders and files are supposed to be deleted from the RAM.
So please be beware