Try opening the computer and unpluging the data cable and power cable from the back of the DC-DVD +/- drive. Then reconnect them (also known as "reseating" the cables)
If after you do that, you still have problems. Try and find the drivers necessary for your CD Drive. It may be that it requires an update. and then try to install the new driver. (it will A) update your current driver, or B) replace your current driver)
If that does not work, please show us your system information (what Computer company if prebuilt, or what company the CD drive is from)
EDIT: PLEASE DO NOT CLICK ON THE FOLLOWING POSTERS LINKS, THEY ARE UNKNOWN LINKS AND MAY CONTAIN VIRUSES OR MALWARE.