My MacBook Pro boots fine until it loads the clock in the menu bar, before becoming close to unresponsive. I found the problem was the systemuiserver process. I deleted com.apple.systemuiserver.plist, which has sorted the performance aspect of the problem. However, I cannot reinstate the clock through iStat Menus as the MacBook becomes immediately unresponsive. I have also lost all other default menu icons such as internet, battery, volume etc. How can I reinstate the icons without recurring the problem? Thanks. Using: late 2010 MacBook Pro 15", OSX Snow Leopard.