If your cd-rom is old, then this can cause problems. My old 32x drive will only read a cd-R copied disk, try putting in a rewrite it can not see the disk.
It goes something like this, a factory produced cd-rom disk has its data stamp onto the disk, which has a reflective coating, this ceates hills and pits to repersent the data, and it cause the lazer beam to reflect back in a different way, depending on weather it hits a hill or a pit.
A cd-r also has a reflective surface, and the hills and pits that create the data is burn't into this surface, in a cd-rom it acts very much like a pressed cd-rom, so most cd-roms can pick up the beam being returned. So age of the crd-machine doesn't really effect it's ability to read data.
But cd-rw tend to use a dye that when heated changes colour, to repersent the hill and pits of data. this tends to lead to a slightly less reflective surface, so older drives can not pick up the flection as well, leading to the believe that no data is present.
And sometimes it could be that the drive just doesn't like the make of the cd-r or cd-rw disk, if this could be the case check your manual or makers web site and they should give more information of what media is compatiable.
If you have a new drive reinstall the drivers for it, as these might of become corrupt, or even out of date.
hopefully these might give you some idea whats happening, as you haven't said what spec your machine is or that of your friends.
Sorry if I haven't explained myself very weel, ut I've just spent 6 hours trying to work out whay only half of my camping trailer lights would work, and where the fault was, a head spinner or what?