DVD Drive Startup Problem

hi.

Section one : i have a macbook pro mc375.

when i power on my laptop, dvd drive has not working.i go to macintosh os & insert the dvd disk, but dvd drive not working.

Section two : reset my laptop and start again.when the system is startup i insert the dvd drive Immediately and dvd drive has been starting on and be working.

**just when dvd drive is working that i insert the dvd disk in startup page.if i don't do this dvd drive not working.**

thanks again...!

Best regard...Arash Shabani