Yesterday, my G5 iMac started freezing up after waking from sleep, but I was able to get it back by powering off and restarting. Today, it's worse. When it boots up, the keyboard is unresponsive, and the mouse works only intermittently. (By intermittent, I mean that it usually boots with the mouse frozen. But if it does boot with the mouse working, then it seems to stay working.) I've tried booting with no peripherals, and it complains that it can't find a keyboard or mouse, so it's apparently recognizing the keyboard and mouse when it boots, but then "loses" them. The mouse is a wired Mighty Mouse, and the keyboard is a wired Apple keyboard. No bluetooth. In addition, my clock no longer displays in my menu bar. When I try to reset this, I'm able to check the box to display, but it won't take effect or retain this setting. On the other hand, I was able to reset the sleep setting to "never." This problem does not correspond with any new hardware or software installs. I upgraded from Tiger to Leopard 10.5.5 about 3 weeks ago, but everything seemed okay until yesterday. I've repaired permissions and verified the disk. Any ideas before I bring this in to an Apple store?