Can not read some originals

[havn't a clue]

I'm trying to back up a few dvds (Electra,Sideways,Final Cut) but can not get them to read in my dvd-writer (HP dvd writer 640b). The writer does not even show a disk inserted. I know the writer works because I backed up a few disks before these today (Fat Albert, Oceans 12). I can read both the original of those movies and the back up.

Any ideas on what I might overlooking?

Thanks in advance.

[Baldrick]

please change the subject. click edit your post.