If you open your disk utility from the application folder and run it on your DVD drive do you get any errors?
Let us know
What happens when you plug the DVD into another port?
owlong have you had this DvD drive?
First could you shut down the machine and disconnect the external drive, THen press and hold down the mouse button and power the machine on. Keep the mouse held till the CD ejects from the built in drive.
This way we can see if the machine is connecting to the internal drive.
Next I would like you reset the PRAM
Shut the machine down again then turn on the computer and press and hold the Command-Option-P-R keys as soon as you have pressed the power button.
Hold the keys down until the computer restarts and you hear the startup sound for the second time and then release the keys.
Once the machine boots back up try reconnecting your external drive again and let me know if it will mount.
So with the DVD connected or disconnected it would not eject the disk,Is that correct?
Do you have your OSX disks?
Could you put your OX disk into either drive and then reboot your mac, As soon as you have pressed the power button press and hold the C key down nd keep it pressed till hopefully it boots to the installer menu.
If it boots to the installer let me know so we can see if it is a hardware or software/firmware failure.
could you shut down the machine and disconnect the external drive, Then press and hold down the mouse button and power the machine on. Keep the mouse held till the CD ejects from the built in drive.
Let me know if it ejected, or opened.
I think we need to write off the internal drive as it is possible that it may work, However booting holding the mouse should have give some kind of response.
Could you disconnect the external drive thenreboot your machine, assoon as it powers back on could you pres and hold the Shift key, Keep the key held down until you see the load icon then let go and wait up to 30mins for your machine to go into safe boot.
Once the machine boots just restart it like normal then try plugging the drive back in.
If that does not work could you reset the PMU, http://docs.info.apple.com/article.html?artnum=95037
Which USB port are you pugging your drive into?
Do you have anything else plugged into your USB ports, If so could you unplug everything then connect only the USB drive.