Try booting the computer with a bootable disk. An operating system disk, like a Windows install disk, or a linux live cd would work. You could also make a bootable disk in another machine, for example, the Ultimate Boot CD: http://www.ultimatebootcd.com/
The boot order will have to be set so that the computer looks for an operating system on the optical disk first, rather than the hard drive. You can change boot order in the bios of the computer. Look in your manual for instructions to get into the bios and how to change boot order if it is necessary.
The reason to use a bootable disk is to check the operation of the drive outside of the Windows operating system. If it works properly outside of Windows, you know that it has no physical problems, but is, instead, a software problem.
Do you have any virtual drives running on the machine? Daemon tools and Alcohol 120 have been known to interfere with optical drive functions.