Question: I have a couple of discs that won't work. The computer doesn't even recognize that they're in the tray. All my other discs work fine and the two in question work ok in another computer.
Answer: I have seen this happen once before so I can at least tell you what the problem was on that occasion and how we fixed it.
The situation involved a DELL computer with the supplied CD drive and a Corel CD. Apparently the particular CD drive was borderline within the alignment tolerance on one end of the acceptable range while the equipment at Corel used to stamp the disk was also borderline at the other end of the alignment range. This put the tracks of data on the disk far enough off of the line where the CD drive was looking so that it couldn't read it. All other disks worked fine in the drive while that disk worked fine in other computers.
How we solved it was to use a second computer to burn a copy of the CD. Because the CD drive in the second computer was more correctly aligned this had the effect of moving everything slightly on the copy so that the DELL CD drive was then able to see it.
If this is the cause of your problem then the same solution should work for you.
This article written by Stephen Chapman, Felgall Pty Ltd.