Burning Track-at-once versus disc-at-once

Since the last Vista updates, I cannot burn CDs or DVDs (via Nero 8) using
track-at-once... (the burning process seems to not complete writing the
TOC)... but disc-at-once seems to work... I've tried disabling Vista's
built-in burner, and other burning apps, but same result...

Is there a reason for this?

Thanks,

Michael