Good Morning!

I am trying for the first time to back up my files but everytime I start the backup, a few seconds in I get this message:
"Insufficient storage available to create either shadow or copy storage file or other copy data (0x8004231F)

I am using CD-R 700 MB disks. I am more than likely using the wrong disks, but I am not sure. Does anyone know what I should be using and if this is not what is causing the problem, what could it be?

Thanks!!
kookykaren