Hi Anand,
You may need to check Dell`s File Library for an update to the firmware of your combo drive. I would also suggest contacting Dell by phone to discuss this issue while you are still within your 30 day return warranty, do not delay.
Best Regards

I have been having the same problem for quite awhile. Techs have tried everything to no avail and will not listen when I tell them to send someone to fix the problem.