CopytoDVD gives incomplete disc


I work for two weeks now with coptoDVD and had burnt 16 DVD’s without any problems… The last time I burnt a couple of DVD’s everything whent ok, no errors. but when i try to play them in the standalone player, i got a disc error… When using kprobe, discinfo said dat the disc wasn’t completed!!! HUH???
I havn’t changed anything on my computer that may conflict…

Anybody an idea what this could be… itwould be very strange that problem would be the media because i 've using this media for quite a while, and works great…, also checked the manufactor site for compatibility… and this was positive
I burn these discs on a lite-on 451s with GSB07 fIrmware, and the booktype tool. (this used to work propperly)

anyboduy an idea?