First, you need to download the SCCM Mac client (Download it HERE) on a PC and then run the install. This will extract a.dmg file, which you can then run on a Mac. This will extract a.dmg file, which you can then run on a Mac. Download the beta for the new Firefox 57 Quantum now In Firefox's relentless battle to take on the impregnable Chrome, they've hit a huge milestone with version 57 of their browser. The beta for it is out now for download and includes the new Servo engine whose performance couldn't be more heartening: Firefox is now twice as fast as it was a. Cannot install avast free for mac.

Find another file on the net that downloads as a.dmg, and try to open that. If it won't, the problem likely is with the new system. It should recognize.dmg files out of the box.

This one is, an innocuous application that will do no harm if you accidentally run it, assuming it will open. The file is a.gz zip file too, and the zip runs first when you double-click it, so if that doesn't work, it would also narrow the problem down to your system. It will download as soon as you click on the link, and takes less than a second. After it unzips, if it does, click on the dmg file and see what happens.