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
New iPhone 4 & iPod Touch Show up in Apple's System inventory –
We are coming closer and closer to Apple’s “Lets Talk iPhone” and we think we have already found two of Apple’s announcements. 9to5mac revealed that they had found a Three new iPod touch models have appeared in the system with the codename N81A. N81 is the codename for the fourth-generation black iPod touch this is more than likely represents the string of the three new white models (8GB,16GB and 32GB).They also reported on some more interesting news that they have found 2 iPhone SKUs in the system. The unexpected is that hey are actually marked as tweaked iPhone 4s (N90A) which suggests very minor changes from the iPhone 4– which is the N90. This could be the long rumored (Cheaper) iPhone which is rumored to be coming in 8GB we are expecting to see a white and black iPhone 4s on the launch.