There may be different problems, so I have included several fixes. Please try each one, but restart the computer before going to the next one. Also, post back on the one that worked for you.
It would seem that these DVD drives have dual lasers. One for the DVD and another for the CD. Get an inexpensive CD head cleaner and see if it would help.
Go to www.dougknox.com
There's a zip file under 'Restore CD/DVD Drives to Explorer' in the XP Fixes section.
You may also want to consider looking into the ASPI and possibly getting a firmware update for the drive. An ASPI setup guide can be found at http://www.hazza.dsl.pipex.com/faq.htm#ASPI
and new firmwares can be found at http://forum.rpc1.org/portal.php
Do you have Nero installed? If so, there have been reports of this program conflictive with DVD drives. You may want to get a fresh copy of it. Uninstall it, and see if your drive works before re-installing the current version.
I know that you probably do not want to hear this, but it does seem like Toshiba and DVD drives have a negative track record. I would like to think that it is software related, but with the frequency of posts I have found with problems on this combo, it is more then likely a hardware problem. Being that it is not under warrentee anymore, your best alternative may be to get another drive. From what I know about these laptops, an external CD drive would be your best bet, and the expense is probably less then what you would spend for the repair at a service station.
We are all curious like a cat. We wonder, we ask, we learn.
Please post back when a suggestion works, so that others may learn.