So here’s a weird one. I’m am running up a new Windows Server 2012 R2 Azure machine to use as a desktop for an Office 365 demo. I need to install Office 2013 on it so I download the trail IMG file (and oh man did it download to my Azure machine quick!).
I renamed the file to .ISO and then right mouse click on it and select Mount from the menu.
I get the nasty message above. I re-download the image and try again. Same result.
I do some research and discover that one option is simply to copy the file to a new location. I do this, to c:\, and now it will mount. Strange!
I suppose maybe some sort of file handle is still open after the initial download? Don’t know. All I can say is that copying the ISO after the download and mounting it worked for me.