[ubuntu] Ubuntu ISO not mounted by OSX (Mountain Lion)

Hello

I have downloaded ubuntu-12.04.1-desktop-i386.iso and burnt that on DVD with a Mac (Mountain Lion). I have used the disks successfully on other computers so I think both the download and burnings are healthy.

By chance (to check the contents of the DVD), I inserted in the Mac and it gave me "the disk you inserted was not readable in this computer". Well, of course I thought that the disk had gone bad; but then I tried the downloaded ISO and it said "couldn't be opened", reason "no mountable file systems".

I do not have another computer here right now, so I cannot check that DVD.

Is this the normal behaviour on Macs? It is only that I cannot even read the DVD label, Diskutil gives as name/label only disk1s1.

Might it be pssible that by sheer coincidence both the iso file and the DVD has gone bad, and thus I have to do a new burning?

If someone knows about this behaviour, I would appreciate your comments.

Thanks in advance

D