[Prboom-users] Problem opening .dmg file

[G 3 <pro...@gm...>]

The PrBoom 2.5.0.dmg file for Mac OS X doesn't open when I click on it. 
Instead I receive this error: "no mountable file systems". I am using 
Mac OS 10.3.9. Has anyone else received this message? Is there a fix?