iPod Disc insertion error (iPod too old?)

[xxbrankxx]

I have an 80GB Video iPod that I bought back in December 2006 and it's been fine. However yesterday I tried charging the battery through my USB port on my iMac and my mouse froze and this "Disc Insertion" error box came up and said "The inserted disc is not readible on this computer". I CMD+Q iTunes and all the open programs so I could shut down but my mouse pointer remained frozen. Is my iPod's hard drive going bad cause it's old (?)? What is the life span of an iPod hard drive? I've been using it basically everyday since I bought it and listen to it everyday probably around 9-10 hours each day when I'm working. And also, is there a way to shut down an iMac without using the mouse? Like can I tab over with the keyboard to shut it down? I know you can hold the power button in but I really don't like doing that too much cause it's not the proper way to shut down a computer. Thank you!