There can be a number of reasons why it doesnt work. Examine the discs that dont work. Are they dirty? Take a lint free cloth and dab it in some water and gently wipe the CD from the inside out. Are they scratched? If so, you might need a DVD repair kit. Theses are fairly cheap and can be found in most stores that sell computer parts or software, as well as online.
Perhaps the issue is with the DVD drive itself. The lens could be dirty. If you have pets or smoke, dirt can get on the lens. You can buy a DVD cleaning kit from the same places you get the repair kits.
Just because one DVD works and another doesnt, does not mean any one problem. Some discs are just easier to read than others. Some discs have more data, some discs might be manufactured better...
Or you can just buy a new drive. They are really cheap these days.
So it can read DVD's but not CD's? Sounds like a busted optical drive. – Ƭᴇcʜιᴇ007 – 2013-04-07T22:57:47.737
Try another optical drive. I had a S**y IDE DVD drive that would not read Windows CD or DVD discs. Various Linux LiveCDs burned from other drives read/booted okay. I keep discs (and drives) clean and scratch free, so that was not the cause. – sawdust – 2013-04-07T23:12:08.273