Errors after verify in NEC 3520A with NERO

I am using winxp pro, nero 6.6, verbatim and TEAC cd media.
burn is NEC 3520A firmware 1.04 .

I burn the dvd I made on HD with maxtor x100 .
after burning, it says ok.
when verify, it says cant access some files, which are errors.
sometimes the DVD is playing ok on DVD PLAYERS sometimes not.

Any idea ?

Most likely poor media,try a better brand such as those made in japan.