odd
you are very sensible to (or at least try to) make the backup
I'm not aware of any problem with what you are doing.
generally the message means that either the disc is full, it's not a writeable disc ... or that the drive is faulty
starting at the beginning - let's just tidy up exactly what you mean - sorry if this is too basic ... but just to be clear
You have a DVD rw disc - do you mean drive (fixed in the case) or disc - bought from a shop?
look in my computer ... you'll see "new volume (C:), (d) etc
then CD and/or dvd
cd or dvd rw
when asked you need to insert a
DVD -r or +r or rw disc (you can get them from tesco for a couple of quid)
2 slots DVD and ROM? - not certain about this ...
the last question is have you managed to burn any type of disc?