Hi
Thats the exact same problem i had and i solved it by installing the IMSM driver for the notebook from the samsung website.
What i did was download and install the driver but i left the win 7 disk in the drive and done a couple of restarts and then ejected the drive, then my machine said it has found new hardware. After that i have not had a problem with the dvd drive at all.
I suggest you get the rest of the drivers as well from the link below for windows 7, but make sure you get the correct ones, i.e 32 or 64 bit.
Let me know if it solves the problem, which will mean it was not just a random thing on my machine.
Good Luck
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