Few days back I had a similiar problem with my DVD writer.I still can't say whether your problem also may be the same.In any case this is what happened.With a brand new blank CDRW, my ,almost four years old ND-1300A DVD writer will recognise it as a blank CDRW and show its capacity using Disc info of Nero 7.However when writing the write operation used to fail at the final stage of writing leadin and leadout.When trying to erase it with NERO even the erase operation failed saying the disc cannot be erased.Checking again the disc info using Nero 7 it showed the media as blank Audio CD not writable.I thought the media must be bad and threw away the CDRW and then forgot about it. How sad.
Later when the same problem repeated with another CDRW,(as per my ND1300A it was an Audio CD after a write attempt failure),I put it into my Liteon DVD writer in the Media center PC and successfully erased it.( I do not remember what exactly the Disc info said but it was definitely not an AUDIO CD as proclaimed by my ND 1300A)Now I knew that the problem is with my ND1300A.I tried cleaning the Laser with a Disc cleaning CD but that did not help.I pulled out the ND1300A DVD writer and replaced it with a brand new Moser Baer Liteon DH-20A1P52C.
So my advice would be try the CDRW in another DVD writer with your friend.If you are able to erase it , the problem is with your drive. Clean the Laser Head and then check.. If the problem persists, you know the solution.
If you are the adventurous type dismantle the DVD drive and manually clean the head. I did not do that since my DVD drive had served me for four years and hence deserved retirement and I did not want to dirty my hand with no results guaranteed.( Just for the heck of it I had once opened a useless Samsung drive and so I do know the how-to)