Why isn't iTunes starting on my mac? I am trying to figure out why iTunes is not starting on my mac.  When I double-click on iTunes.app in the finder, I get the usual animation of the icon indicating that the app is starting, but then nothing happens.  

Digging a little deeper, I see the following entries being created in the console:

2015-05-10 7:21:11.710 PM pkd[445]: com.apple.message.domain: com.apple.appextension.state
com.apple.message.action: Uninstalled
com.apple.message.name: com.apple.iTunes.today.TodayExtension-1.0
com.apple.message.reorder_direction: 0
com.apple.message.source: Apple
com.apple.message.type: com.apple.widget-extension
SenderMachUUID: 58242545-21FA-3D58-8722-ED1C2E256DB6

2015-05-10 7:21:11.720 PM pkd[445]: com.apple.message.domain: com.apple.appextension.state
com.apple.message.action: Installed
com.apple.message.name: com.apple.iTunes.today.TodayExtension-12.1.2.27
com.apple.message.reorder_direction: 0
com.apple.message.source: Apple
com.apple.message.type: com.apple.widget-extension
SenderMachUUID: 58242545-21FA-3D58-8722-ED1C2E256DB6


This pair of entries is created each time I double-click. There is no other indication that I can see on why iTunes is not starting.

I have recently re-downloaded and installed version 12.1.2 from apple and continue to have the same problem.

I am running Yosemite version 10.10.3 and I can provide any other information that may be useful. Does anyone have any ideas?



EDIT: 

Logged in as Guest User and experiencing the same behavior.

Other seemingly related apps (eg- iBooks, keynote, app store, photos) have no trouble opening either as the regular user or as the guest user.
I have a workaround. Not a fix, but something that allows me to open itunes.  I've created this bash alias:

alias itunes='/Applications/iTunes.app/Contents/MacOS/iTunes --x &amp;'


Now, whenever I type itunes in the terminal, the application opens.

The --x option is not valid AFAIK. For some reason, passing a command line option kicks iTunes to  open. When passing no parameters, iTunes does not open.

I cannot explain this behavior and would appreciate an explanation if anyone has one.

I'm going to try @Tetsujin's suggestion to see if it provides a complete fix.