Help... Having these main problems (which I'm sure many have witnessed using Leopard): (I have a desktop iMac (intel core duo 2.66).) 1 The machine often refuses to shut down (or restart) and I get that black veil slide down the screen following the "you need to restart your computer..." message 2. The machine refuses to shut down and just stays on the desktop image with the black spining wheel spinning endlessly. 3. I'm getting problems with applications refusing to quit (even when using opt-cmd-escape) . even when the computer "acknowledges" that the ap has quit, the icon is still active in the dock underneath Any basic remedies for these?