I have check several other threads, but nobody has touched on this specific Xamarin installation error.
I'm installing Xamarin Studio on a Mac. I downloaded the dog file from Xamarin and ran it.I get the standard "Are you sure you want to open it?" message. I then click on the "Open" button. A window opens, titles, "Visual Studio for Mac - Installation" with no content and a spinning cursor. It closes and I get a "Problem Report for Install Xamarin" window with the following information:
Process: Install_Xamarin  Path: /Volumes/VOLUME/Install Xamarin.app/Contents/MacOS/Install_Xamarin Identifier: com.xamarin.universalinstaller Version: 3.0.0 (1) Code Type: X86-64 (Native) Parent Process: launchd 
Date/Time: 2017-04-28 09:15:08.005 -0500 OS Version: Mac OS X 10.7.5 (11G63b) Report Version: 9 Sleep/Wake UUID: 59EEA8E4-7B54-4380-8B95-31AEC2D5598D
Interval Since Last Report: 3584789 sec Crashes Since Last Report: 9 Per-App Interval Since Last Report: 93 sec Per-App Crashes Since Last Report: 9 Anonymous UUID: 597FF5D8-3727-4348-A273-6923618B6E3D
Crashed Thread: 0 tid_b07 Dispatch queue: com.apple.main-thread
Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000
Application Specific Information: *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[NSColor colorWithRed:green:blue:alpha:]: unrecognized selector sent to class 0x7fff75f69c10'