RolloTomasi

Yep, it did. Basically, after installing and restarting, I went immediately to System Preferences > Security > General (the first tab in Security) and unlocked to make changers, and the "Driver failed to install" message was right there, below the "Allow apps downloaded from" options. Hope that helps!

Never mind - I found the post that explains the security settings.

I just rebuilt my Mac, and tried installing both HD500 driver versions 7.2.5 and 7.2.7 multiple times, and nothing is showing up as a driver. I've also use both Line 6 Monkey and the downloadable installers on the site. Does anyone have any tips on ho to fix this? This has never happened to me before. Thanks.