Some have reported this issue already, quite some time back. I'm still trying to get our Engineers to resolve this issue, but my big stumbling block is that they are not able to duplicate this issue.
And yet, others continue to have this issue, though not everyone. We are planning some major changes soon, and I'm praying that this will resolve the issue once and for all. Till then, you might want to try the below solutions a few have found to work for them.
I'm curious to know if this resolves your issue as well as it has for a few others.
From Another Nero User:
Disabling the Nero Codecs does SOLVE the lip sync problem and an easier way to do this is just by renaming a couple of files....
For Nero v7.*.*
In C:\Program Files\Common Files\Ahead\DSFilter, rename NeAudio2.ax to OLDNeAudio2.ax and rename NeVideo.ax to OLDNeVideo.ax.
For Nero v6.*.*
In C:\Program Files\Common Files\Ahead\DSFilter, rename NeAudio.ax to OLDNeAudio.ax and rename NeVideo.ax to OLDNeVideo.ax
Hope this helps.