Cannot read DVD

[Dimitrios Eftaxiopoulos <eftaxiop@central.ntua.gr>]

I use Debian Lenny, on an i386 laptop. I try to mount a dvd and I get 

eftaxiop@filippos:~$ sudo mount /dev/hdc -t iso9660 /media/cdrom0
mount: block device /dev/hdc is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on /dev/hdc,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

Then 

eftaxiop@filippos:~$ dmesg | tail
[drm] Setting GART location based on new memory map
[drm] Loading R200 Microcode
[drm] writeback test succeeded in 2 usecs
NET: Registered protocol family 10
lo: Disabled Privacy Extensions
UDF-fs: No fileset found
Unable to identify CD-ROM format.
UDF-fs: No fileset found
Unable to identify CD-ROM format.
Unable to identify CD-ROM format.

When I check the disk

eftaxiop@filippos:~$ sudo cdck -d /dev/hdc
Reading sectors 1-258656
258656 ok

CD overall:
   Sectors total: 258656:
   Good sectors: 258656:
   Bad sectors (incl. with poor timing): 0
CD timings:
   Minimal = 3 usec (0.000003s)
   Maximal = 73951 usec (0.073951s)
   Average = 756 usec (0.000756s)

Conclusion:
   Excellent disc!

In the same computer (dual boot) I can read the DVD under Windows.

Any help welcomed.

Dimitris