Hey folks: I'm new to the forum and fairly new to the wonderful world of mac. We have a 27" iMac, late 2009 (2.66 ghz core i5 processor; 12 gb RAM; ATI Raedon HD 4850 512 MB graphics) running OS X 10.8.4. Bought it used last year, and for the most part it works fine. But every once in awhile it just freezes up on me. I can still see the cursor moving around when I move the mouse, but can't click anything. Keyboard doesn't do anything. My only choice is to hold the power button down and do a hard reboot. I thought maybe it was a mouse/keyboard connectivity issue, maybe a bluetooth thing, but it doesn't appear so. It has happened shortly (i.e. within an hour) after turning the computer on, and after hours of use... at one point I thought it was more prone to occur when I was using Google Chrome (I kind of live in Chrome), so I tried uninstalling Chrome, but it still happened, so there might not be a cause-and-effect relationship here; it may be simply that I'm in Chrome a lot, so it's more likely to happen when I'm in Chrome than any other application - I dunno. I'm not knowledgable enough about macs to know if there's a way to troubleshoot this. Any help or suggestions or pointers in some direction would be MUCH appreciated. I will not take offense to any responses; feel free to assume I'm completely ignorant.