Thanks for your response CDuncle.
Maybe I didn’t get the save right.
Truth is, I’m not used to saving these sort of things.
In the past, whenever I’ve added to a compilation, using NTI CD\DVD, Nero, Power2Go etc etc, the burning program has recognized the previous session and opened up the disc without problems.
In fact, Power2Go did this the second time. But not the third
The disc definitely isn’t full. The original Avast software is about 150MB and the updated signature files are around 13MB-14MB.
So after the second burn the data on the disc wouldn’t have exceeded approx. 170MB.