Hi ash_c85 and welcome to cdfreaks,
As suggested by Jimbo …are the discs closed (ie., finalized)? and will they play in your pc?
And advice from beef, try burning with Img and see if these discs are playable.
In [B]Common settings [/B]> [B]Write[/B] > Please change from packet writing to [B]SAO[/B] and see if this resolves your issue
Also, if you could post a few burn logs, it would help us nail down the problem for you.
The default location is:
C:\Documents and Settings[I]Administrator Name[/I]\My Documents\DVDFab\Log