Just got a new 1.83GHz macbook yesterday. Added a 1GB SODIMM. Unfortunately it does a very strange crash, where the screen itself will freeze but the cursor will move around. Music will continue playing. If I ssh into the machine and kill windowserver, the machine will continue working fine, until it crashes again, which has happened about 3 times now. I've done a bit of digging round and it appears to only happen when I don't have my external (DVI) display plugged in. I get these errors in system.log when it crashes: /System/Library/CoreServices/SystemUIServer.app/Contents/MacOS/SystemUIServer: kCGErrorCannotComplete : CGSDeviceSynchronize: Invalid device window Any ideas?