I have just discovered that I have this problem on my brand new Intel iMac using Toast 7.1.2 also. Using the same DVD+RW (which hangs on the lead-out with 7.1.2), and burning using Toast 7.1 on my PowerBook yields a NORMAL BURN.
If I burn from the Finder, using the very same DVD+RW, burning is successful.
So...I am no expert, but I would say this is a bug in Toast 7.1.2.
John. Can you point out how to do a proper uninstall of 7.1.2 so that I can hopefully go back to 7.1 again and not suffer with this Toast bug?