It should not be, however the voltage could be sagging under load or there could be excessive ripple. I don't think ripple would cause a motor to struggle that much but I'm no engineer.
This is a standard CD-rom drive that you are trying to open by pressing a button on the drive itself, right?
Does the drive open before the OS boots? will it open right after the PC POSTs? If So it could actually be a software issue, something loading that is keeping the drive spinning.
Or how about this simpler method. Will it open if you disconnect the data cable?