A friend just got a second-hand G4 (Sawtooth G4/400) with OS 9.1, and it intermittently crashes during boot. It always gives the smiling Mac, and always gets to the Welcome to Mac OS screen. Sometimes it crashes there, but most of the time it makes it to the Starting Up screen. It often crashes once the progress bar moves about 1 cm along - the mouse stops moving and the system completely freezes. Sometimes it makes it past that point, in which case it usually boots the rest of the way successfully. So far, we've tried changing the memory, booting with extensions off, booting from an OS 9 CD, resetting PRAM, resetting Open Firmware (reset-nvram, set-defaults, reset-all), and resetting the PMU. The hard drive makes some interesting noises, but they might be normal (it's an old drive). We haven't yet tried booting from CD with the HD disconnected. Any ideas? He's bringing his Mac back on Saturday, so it'd help if I have a list of suggestions to try by then Edit: Sometimes when it crashes, it comes up with a white box with nothing in it (it looks to be the same size and style as the old 'Welcome to Macintosh' box from System 7).