Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Working with a Mac gets even more difficult when the most frequently used applications fail to cooperate, hang or freeze repeatedly. For many users, the solution remains a simple refreshening of the application via uninstall and reinstall; however things get slightly challenging when the applications don’t uninstall that easily, which otherwise happens as simply as dragging the application’s icon to the Trash and selecting Empty Trash.
For such applications, the reason why a simple drag and drop un-installation doesn’t work is because of their spread across the hard drive. There might a complete folder to be deleted besides files in the Library or running files in the background. While in many cases, you do get the ‘Uninstall’ option, there might be some troublesome applications.
iTunes is one of them!
While in most cases uninstalling and reinstalling iTunes works well, there are times, as Apple calls ‘rare instances’ where you may need to do a little more. This may involves deleting library files as well other dependant applications. This surely is complex for the noobs.
So when caught in such a predicament, follow the mentioned steps and fix your nagging iTunes glitches.
First, open the Activity Monitor and ensure that you quit the iTunes Helper process. Now, ensure that you delete the same process from the Login item lists, which lies in the Accounts System Preferences pane. Once done, restart Mac.
Sometimes, these steps may not be sufficient. You might have to go to ~/Library/Preferences and look for all files that begin with com.apple.iTunes (also in the ByHost subfolder). Select these files and delete. Apple also suggests that you delete the ~Library/iTunes folder. This folder has all iPhone and iPod update files. As a precaution, take a backup of this folder just in case you miss out some important files.
There are times when iPhone, iPad or iPod are not recognized by iTunes. For such cases, you will have to uninstall and reinstall the Apple Mobile Device Service. To delete this file, you need to delete two files. First, the AppleMobileDevice.kext file in the /System/Library/Extensions folder and secondly the AppleMobileDeviceSupport.pkg file in the /Library/Receipts/ folder. Now restart your Mac.
Now simply reinstall a fresh iTunes copy. You are done!