I've got a problem with an OLD 2006 Core 2 Duo iMac. In spite of this computer's age, I have upgraded it to 2 GB of RAM and it's running Snow Leopard. The problem is the dock and menus along the top of the screen won't respond the way they used to. Hoovering the mouse over icons in the dock does not make them magnify (even with magnification turned on) and it no longer displays the name of the application the mouse hovers over in the dock. Clicking on the items does open them, but I don't get any feedback when just hoovering over them. As for the menus at the top, clicking on the apple in the corner works fine, but hovering over "About this Mac" and other options doesn't make them highlight blue like they should, although clicking on them works fine. This problem applies to all menus at the top across all applications. Yes, I HAVE changed the mouse. Same problem. I've attempted to fix this problem by following the instructions on this web page and deleting the "com.apple.Dock.plist" file under /username/Library/Preferences/ and then restarting the computer. That did solve the problem, but only temporarily. After some more use, the problem came back, and deleting the file and restarting again yielded the same result: only a temporary fix. Any ideas on a fix? Anybody else experience this? Could it be because my mother uses the computer primarily to play Farmvill (which according to her also has response issues which were temporarily fixed once I deleted that file and restarted the computer)?