DVD drive ejects on shutdown or hibernate

My laptop drive automatically ejects on shutdown or when it goes to hibernate/sleep mode. This happens only when the laptop is connected to a power outlet. When it is running on battery, it doesn't eject on shutdown or hibernate, but ejects when it goes into sleep mode.

I tried a fresh install of W7 SP1 x64 but it did not solve the issue. I have set the booting sequence to HDD, USB, ODD and BIOS ver is Insyde 1.8.

Drive hardware ID is MATSHITA DVD-RAM UJ8C0__1.01_

Please help in resolving this issue.

Thanks