The reason for this error message is that you are trying to read a disc that is "Multisession". This is a type of security, here are all of the posts in the forums about this:
http://forum.mtu.com/search.php?acti...der=descending
There is a huge amount of information on this, but this type of disc will not beable to be copied by the Duplicate Disc Tab in Microstudio.