I've got the same problem with a DVD-R in a 2009 Macbook Pro running the most up-to-date version of OS X Lion 10.7.3. It reports 'the volume can't be ejected because it's currently in use'.
I was copying various mp3 s and pdfs of this DVD-R where I have archived them using drag and drop. It refused to copy a folder full all at once so I had to painstakingly drag and drop them one at a time.
Although I am a fairly new mac user and generally a fan of the solidity of the operating system vs windows of which I am a long term user, this is one of two things I think could be improved.
I am familiar with this kind of glitch in USB pen drives refusing to eject in windows, usually because there is some real-time indexing, backup or other ongoing operation.
i found a fantastic little free utility for windows called 'unlock' which identifies and kills either selected or all such processes allowing safe removal of a drive in Vista. Obviously it should be included in windows and maybe in 7 it is, I don't know.
I found an incredibly complex and long-winded set of instructions for removing a CD posted elsewhere on this forum, but since I know the problem is the same as the one described on this thread and the message displayed is the same, it seems most appropriate here.
As far as copying processes still running, bear in mind I last started a copy operation nearly 24 hours ago, yesterday afternoon or evening, and it is now 3pm the next day here in the UK.
So how do I 'kill process' SIMPLY, and so free up my DVD-R to eject, please? A swift answer would be appreciated, as I can't use my laptop rom drive until I can.
Also, please forward the recommendation from me and the other posters on this thread that such an 'unlock' or simple 'kill process' app be included in Mac OS X's next update, or ASAP. Or perhaps it just requires an App, like the windows 'unlock' app, which is still available , if you google it. btw.
Oh - and the difference between this and most shut down stall processes - there is no 'force quit' option offered by the displayed message or the top menu bar.
Thanks,
Rich
P.S. and if there is already a simple function, key sequence or app that does this, please tell. Perhaps I missed it, I did buy a video intro to OS X lion but it was very basic and bear in mind I am a new Mac OS user.