My tried and true iMac started freezing up after prolonged use and after a couple days started freezing up right after start up. The mouse still moves though when it freezes up making me think it was the graphics card a 2600 nvidia pro I believe. But the more I think about it the more I hope it's a hard drive because the graphics cards are expensive and hard to replace. I ran disk utility and it didn't find anything so I was hoping that somebody on here had similar issues and it was their hard drive. Any advice would be helpful. Thank you.