DVD - Dell Vostro 1000 problem

Hello I have a Dell Vostro 1000 It has the following DVD player/writer HL-DT-ST DVD+-RW GSA-T11N ATA DEVICE The machine is just over 2 months old and I have just put a DVD in the machine for the first time At first I got an error message with the region code The software it was using was POWER DVD DX I then did a software update on this (thinking this may resolve the region error), by clicking on update on the software. The software didnt install Now when I put a DVD in the drive it does nothing - CD's play fine If I got the the control panel - I can see the drive, and if I right click I can see what it is trying to play - just nothing happens My operating system is Windows Vista Basic Does anyone know how to fix this please Thanks