Sandy,
It sounds as if you drive is going bad. At least for Karaoke, you only get this error when you have a problem with the drive or your drive doesn't support Karaoke. All of the Plextor drives work for Karaoke.
Have you been using this drive and just got the problem?
Also, their would have been an email sent to you at one time about upgrading from 2.400, but they are not sent every time there is an upgrade. You can see when Updates are available from
http://www.mtu.com/support/news.htm
To get an update from 2.400 you would need to purchase the Upgrade from $15 from:
http://www.mtu.com/store/merchant.mv...Yes&Quantity=1