Im making a VCD using NERO V6 and putting it on a CD-R with 700mb of space. Ive done this some many times and it worked. But this time it failed. The CD-R write buffer is meant to stay high but i saw it going down till it reached zero and then it failed.
For t'shooting purposes, try setting a lower write speed 4x or 2x, or at least lower than the speed you usually write at. Also, make sure you don't do anything else on your PC while the writing/copying is in progress. Despite doing the above if the problem persists please post back.