You may try trashing plist and prefs first.
Quit Toast 14, trash the entire Toast 14 folder (located in Finder > Applications), then check for the files listed below. If you see any of them, trash them:
"Roxio Toast Prefs"
You should be able to locate these files in ~/Library/Preferences. On the taskbar at the top, click on "Go", and select "Go To Folder...". Type in "~/Library/Preferences", without the quotes. Locate the above files in the Preferences folder that comes up and delete them. Once deleted, re-launch Toast and see if the problem has been corrected.
I tried that but it did not work.
I have questioned the customer support who asked for further information.
In the meantime, Roxio just released Toast 14.1, with a new version 1.0 (1) - a strange version number- of MyDVD.
And HALLELUJAH, I was able to create a disc image without crashing at 70 % of completion.
But ALAS, when I tried burning a disc, it crashes around 78 %, thus freezing the Mac completely (Mavericks).
So, Roxio is progressing, we just have to wait !