Optical Drive query

[squareyes]

Hi all,
could some one enlighten me, the optical drive on my Lenovo laptop
can "See" bootable CD/DVDs, and install operating systems, but will not 
"See" any other CD's when systems installed.
This is true for both Win XP and Ubuntu 8.04. I have an external drive 
connected via USB, which works fine
for all discs.

My query is... Does the external drive use the same driver that the 
internal drive should be using? , or am I missing something? Don't wish 
to use Win XP, (they have sent me a set of recovery discs for Vista that 
will not install properly) but now need it for Lenovo support as they 
tell me that with Linux I am on my own. Have been told that as machine 
is not in original config, that is my problem, but recovery discs won't 
solve problem.

Thanks in advance
Take Care
Winton