Try running the Fix It now program from Microsoft found here: http://support.microsoft.com/mats/cd_dvd_drive_problems/en-us
If that doesn't help, you may have to delete the Upper and Lower filters. An easy way to do that is to install a free burning program called ImgBurn. www.imgburn.com
Install ImgBurn, then click on any of the Icons...lets choose Discovery. Click on Tools-->Filter Driver Load Order. Look and see if there are any Upper or Lower Filters, and if there are, you can remove them here in ImgBurn. Reboot the machine after removing any filters and see if the computer can find the optical drives.
The other way to remove Upper and Lower Filters is through the registry, which is a little more risky, but there are instructions here: http://support.microsoft.com/kb/982116