Shuttle XPC SN85G4 problem

[Perywinkle]

Bought one of these a week ago on the bay but the dvd player would only read cd's.
Fine I thought, and replaced it, trouble is the new one does the same.

Anyone got any ideas as to what it could be?

 

[Perywinkle]

Stupid of me to only try writable disks I supose, normal film dvd's work fine.
Cheers chaps