Keyboard becomes undetectable in 2012 iMac

Hi all,

I purchased a 2012 iMac at the end of December with the 1TB Fusion Drive, and the 2Gb Video Card. It has worked great so far, but I had an issue the other night that I can't seem to find anywhere else.

I had a USB Midi Keyboard plugged into the computer that I was using with Garageband. My girlfriend went and plugged her iPhone 5 into the USB slot on my computer keyboard, and iTunes opened up stating that the iPhone was locked with a passcode. Right after this, my computer keyboard stopped working. I couldn't type or anything, so I closed all of the open apps using the mouse, and rebooted the computer. After the computer rebooted, the keyboard still did not work so I couldn't even type in the login password to get back into OSX. I must've rebooted at least 15 times trying to see if it would detect the keyboard. I did some Google searching, and tried unplugging the power cable for 30 secs and that did nothing either. I disconnected all of the USB slots except the keyboard and still nothing. I called Apple Support, and the tech told me to try unplugging the power cable again for 30 secs. After this did not work he told me that it must be a faulty keyboard and that I should go to an Apple store to get a new one.

So after that, I decided to try something else. I plugged my USB Midi Keyboard back into the computer while I was at the login screen, and turned the power on the Midi Keyboard (it's powered by the USB cable). I think I then rebooted the computer (was a few days ago), and after that the computer keyboard started working again. Almost like I recreated the conditions before the iPhone had been plugged in and it fixed it.

Anyway, the next morning after this, my girlfriend plugged her iPhone 5 into the USB slot on the back of the iMac, and the computer keyboard stopped working again. I wasn't able to fix it this time, I turned the computer off and left my apartment for 2 days. When I came back the keyboard worked again. So I'm thinking this is likely a software issue with Mountain Lion, or some issue with the USB controller on this new iMac. Any help would be appreciated so this doesn't happen again.