Unmounting a Disk

[robbygraham]

I have been wanting to format my macbook pro, just to start it over with a fresh install, I have a Western Digital 320gb external, this has been giving me problems, I am trying to erase the data on it, but every time I try to erase it through Disk Utility, I get the message:

Error Occurred, Could Not Unmount Disk.

I have tried everything, found guides but nothing seems to work, looked through loads of threads, but i just get the same message every time, I have also tried plugging it in a Windows pc to format it, but that doesn't recognise it, as its Mac OS Journaled. Any help would be really appreciated, as I don't want to buy a new drive. I don't understand why I can't erase this one.

 

[Munson]

Is the external drive NTFS partitioned? If so, I'm pretty sure OSX won't be able to get write access to that volume. Certainly not without a third party NTFS driver installed.

EDIT: woops, missed the last bit

 

[robbygraham]

Eventually managed to sort the problem, tried windows and mac pc's both couldn't deal with the issue, nor could my ps3, but when plugging it into a flatmates 24" sony tv it fixed it haha