DVD playback issues : Dell Inspiron 17R (N7110) : Is the fitted NVIDIA GeForce GT 525M card fit for purpose?

Ahoy!

My Dell Inspiron 17R (N7110) is unable to play DVD's correctly.  I tried playing a DVD for the first time a few days ago and playback is impossible!  When the DVD is inserted into the drive tray and the software programme activated to play the DVD film, after maybe 2 or 3 seconds the playback keeps freezing and jerking, plus the sound freezes and the screen goes 'blocky' and basically, the Inspiron is unable to properly play DVD's and I believe the issue lies with the fitted NVIDIA GeForce GT 525M graphics card, though it also has an Intel HD 3000 fitted.

I also have an HP Pavillion g7 with Windows 7 64bit (same as the Inspiron) that also has had the RAM increased to 8GB though it uses an AMD Radeon graphics card, and DVD playback is totally perfect, hence why I believe the fitted NVIDIA card fitted to my Inspiron isn't fit for purpose, in which case why wasn't a suitable card fitted from new (assuming this was known) and fit a DVD drive to the laptop if playback cannot be made?

My Inspiron was supplied with 4GB of RAM, but I had it upgraded to the maximum 8GB and all OS and graphics drivers and software is 100% up-to-date (the same applied for my HP g7 Pavillion laptop).

So, unless anyone knows about this and has a solution, I would like to hear from Dell (UK) with an explanation as to why a graphics card was fitted to the Inspiron when it cannot properly play a DVD, and to that end, would Dell (UK) consider upgrading the card in order for the DVD playback to operate correctly?

Thanks in advance.