Hello! I have a 27" iMac, about a year old and I'm on Maverick OS. I've had an intermittent problem since I got the machine that occasionally the mouse and keyboard would one or both stop responding. It seemed to only happen when I'd been using Photoshop (CS 5) for a while, with one or more moderately sized files open (or having opened and closed several files). Typically, the keyboard stops working. I'll be mid editing and try to use a keyboard shortcut in Photoshop only to have it not respond. If I switch programs using the mouse to say Pages or a web browser about half the time I'm able to type in those programs. Closing and restarting Photoshop has no affect on this; only restarting the machine gives me the keyboard / mouse back. It's so intermittent that I've been able to work around it so far without much more than a slight annoyance and honestly I've dealt with worse foibles with Windows machines. Today it did something new. I was mid-typing in a web browser window and the keyboard and mouse both froze up. The keyboard suddenly started backspacing the text I had in the form field and wouldn't stop. The mouse was unresponsive. The Mac continued to function though, as I have a timeout program to force me to take a break every hour and that kicked in normally. I tried removing the batteries from the keyboard (wireless standard that came with) and turned the mouse off and on (magic mouse). I also tried plugging in a USB mouse and keyboard that I've used with the machine before but still got no response. I had to hard reboot the machine to get the keyboard / mouse to work again. I checked when the machine came back on and my mouse battery was at 25% and keyboard at 30%. I did have Photoshop open in the background and had been in and out of it a bit throughout the day, hence why I mentioned the other issues above that may be connected. I can't think of anything else that might be affecting the machine. Of course, the original problem predates Maverick, but the software had been kept up to date to the latest version from purchase (I think that was from Mountain Lion but I can't remember). I can live with a little inconvenience when I have a chance to save everything and reboot, especially as it doesn't happen often at all. But if I'm now starting to loose work and have the whole thing lock up loosing me more potential work from long emails, then I'd rather try and figure this sucker out. Any suggestions or thoughts? I'm at a loss with this. Thanks!!