Sentinel DVD medias: Error when reading DVD "cyclic redundancy check"

I burned several +RW DVD with my HP 100i DVD recoder with Nero 5.5.10.35 (and other 
programs)
The burn process itself works fine. Nero told me: successfully finished.

The verify process afterwards stops after approx 85% of the data files and told me
Data error (cyclic redundancy check).

I tried this with three different DVD media from SK (Sentinel) but the same problem 
happens 
with all the DVDs

Moreover I could not read the last 15% of the files when I dragged them inside
the windows explorer (under Win2000).

Because I tried multiple different burning programs with the same bad result it must be
an error of either the DVD burner or the DVD media.

Does anyone have had the same problem?

Is this a problem of the bad quality of Sentinel DVD medias ?

Jeff