Why, at last I've figured out what's wrong with some Nero-written DVD's and CD's ! There's a huge number of CD/DVD's I could not mount automatically upon insertion. I did the job with mount /dev/hdc /media/cdrom , but then I had to remove the disk manually issuing the proper umount command. Bad, isn't ? The problem lied in my fstab:
At the installation by default it gives>
/dev/hdc udf,iso9960 user,noauto 0 0
I've changed it to
/dev/hdc auto user,noauto 0 0 , and my problems have gone !