I had this problem a lot (1 in 5 burns) with an external USB2 drive, so don't use it now to burn. I forget, will have to check my logs to see if it failed, and I did the same burn again and it worked on the next blank disk.
This has even happened, but only once with the internal drive, while I was running a lot of other stuff during a burn it stopped at 99%.
I quite often have to re-boot the computer to eject the disk after this happens too. XP system and then I upgraded to service pack 2.
I never discovered what the cause was (if shrink didn't shrink quite enough), or a problem with Nero, or media, or operating system, or load on system.
I still want to try a few things, like burning data that is only about 90% of the disk capacity and see if it always burns, and then also burning some test disks with cd-speed, and trying different disks.
Also find another computer with usb2, and the software and then can quickly test the USB2 drive.